Empty window in bundle installer when using custom theme

[vlaterz]

Hello!
I am using Visual Studio 2022 and moved my wix3 projects to wix4.
When i moved my Bundle project to wix 4 my installer broke down. Error was:

[4468:5D8C][2023-11-08T12:44:06]e000: Error 0x8007000d: Window elements must contain either the Caption or StringId attribute.
[4468:5D8C][2023-11-08T12:44:06]e000: Error 0x8007000d: Failed to parse theme window element.
[4468:5D8C][2023-11-08T12:44:06]e000: Error 0x8007000d: Failed to parse theme.
[4468:5D8C][2023-11-08T12:44:06]e000: Error 0x8007000d: Failed to load theme from path: C:\Users\VLADIM~1.TER\AppData\Local\Temp\{D95169BF-9CE9-4F80-9D1E-F1057B19BF2C}\.ba\thm.xml
[4468:5D8C][2023-11-08T12:44:06]e000: Error 0x8007000d: Failed to initialize data in bootstrapper application.

So, i changed a Caption to window and updated schema to v4
My customrheme.xml file

<?xml version="1.0" encoding="utf-8"?>
<Theme  xmlns="http://wixtoolset.org/schemas/v4/thmutil">
	<Window
			Width="485" 
			Height="350" 
			FontId="0"
			Caption="#(loc.Caption)"/>
	<Font Id="0" Height="-12" Weight="500" Foreground="000000" Background="FFFFFF">Segoe UI</Font>
	<Font Id="1" Height="-24" Weight="500" Foreground="000000">Segoe UI</Font>
	<Font Id="2" Height="-22" Weight="500" Foreground="666666">Segoe UI</Font>
	<Font Id="3" Height="-12" Weight="500" Foreground="000000" Background="FFFFFF">Segoe UI</Font>
	<Font Id="4" Height="-12" Weight="500" Foreground="ff0000" Background="FFFFFF" Underline="yes">Segoe UI</Font>
	<Font Id="5" Height="-12" Weight="750" Foreground="000000" Background="FFFFFF">Segoe UI</Font>
	<!--<Image X="11" Y="11" Width="64" Height="64" ImageFile="logo.png" Visible="yes"/>-->
	<!--<Text X="80" Y="11" Width="-11" Height="64" FontId="1" Visible="yes" DisablePrefix="yes">#(loc.Title)</Text>-->

	<Page Name="Help">
		<Text X="11" Y="20" Width="-11" Height="30" FontId="2" DisablePrefix="yes">#(loc.HelpHeader)</Text>
		<Text X="11" Y="112" Width="-11" Height="-35" FontId="3" DisablePrefix="yes">#(loc.HelpText)</Text>
		<Button Name="HelpCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.HelpCloseButton)</Button>
	</Page>
	<Page Name="Install">
		<Image Name="Splash" X="0" Y="0" Visible="no" ImageFile="splash2" Height="350" Width="180" HideWhenDisabled="yes"/>
		<Text Name="UpperText" X="185" Y="20" Width="-11" Height="30" FontId="5">#(loc.EULAReadText)</Text>
		<Richedit Name="EulaRichedit" X="185" Y="35" Width="-11" Height="-90" TabStop="yes" FontId="0" />
		<Checkbox Name="EulaAcceptCheckbox" X="-5" Y="-41" Width="280" Height="17" TabStop="yes" FontId="3" HideWhenDisabled="yes">#(loc.InstallAcceptCheckbox)</Checkbox>
		<Checkbox Name="RuntimeInstallCheckbox" X="-5" Y="-60" Width="280" Height="17" TabStop="yes" FontId="3" HideWhenDisabled="yes">Install .NET Runtime</Checkbox>
		<!--<Button Name="OptionsButton" X="-171" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes" Visible="no">#(loc.InstallOptionsButton)</Button>-->
		<Button Name="InstallButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.InstallInstallButton)</Button>
		<Button Name="WelcomeCancelButton" X="-11" Y="-11" Width="90" Height="23" TabStop="yes" FontId="0">#(loc.InstallCloseButton)</Button>
		<Static Name="Line" X="-15" Y="-60" Height="25" Width="275"/>
	</Page>
	<Page Name="Options">
		<Text X="11" Y="20" Width="-11" Height="30" FontId="2" DisablePrefix="yes">#(loc.OptionsHeader)</Text>
		<Text X="11" Y="121" Width="-11" Height="17" FontId="3" DisablePrefix="yes">#(loc.OptionsLocationLabel)</Text>
		<Editbox Name="FolderEditbox" X="11" Y="143" Width="-91" Height="21" TabStop="yes" FontId="3" FileSystemAutoComplete="yes" />
		<Button Name="BrowseButton" X="-11" Y="142" Width="75" Height="23" TabStop="yes" FontId="3">#(loc.OptionsBrowseButton)</Button>
		<Button Name="OptionsOkButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.OptionsOkButton)</Button>
		<Button Name="OptionsCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.OptionsCancelButton)</Button>
	</Page>
	<Page Name="FilesInUse">
		<Text X="11" Y="20" Width="-11" Height="30" FontId="2" DisablePrefix="yes">#(loc.FilesInUseHeader)</Text>
		<Text X="11" Y="121" Width="-11" Height="34" FontId="3" DisablePrefix="yes">#(loc.FilesInUseLabel)</Text>
		<Text Name="FilesInUseText" X="11" Y="150" Width="-11" Height="-86" FontId="3" DisablePrefix="yes" HexStyle="0x0000C000"></Text>

		<Button Name="FilesInUseCloseRadioButton" X="11" Y="-60" Width="-11" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes" HexStyle="0x000009">#(loc.FilesInUseCloseRadioButton)</Button>
		<Button Name="FilesInUseDontCloseRadioButton" X="11" Y="-40" Width="-11" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes" HexStyle="0x000009">#(loc.FilesInUseDontCloseRadioButton)</Button>

		<Button Name="FilesInUseOkButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.FilesInUseOkButton)</Button>
		<Button Name="FilesInUseCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.FilesInUseCancelButton)</Button>
	</Page>
	<Page Name="Progress">
		<Text X="11" Y="20" Width="-11" Height="30" FontId="2" DisablePrefix="yes" >#(loc.ProgressHeader)</Text>
		<Text X="11" Y="121" Width="70" Height="17" FontId="3" DisablePrefix="yes">#(loc.ProgressLabel)</Text>

		<Text Name="OverallProgressPackageText" X="85" Y="121" Width="-11" Height="17" FontId="3" DisablePrefix="yes">#(loc.OverallProgressPackageText)</Text>
		<Progressbar Name="OverallCalculatedProgressbar" X="11" Y="143" Width="-11" Height="15" />
		<Button Name="ProgressCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.ProgressCancelButton)</Button>
	</Page>
	<Page Name="Modify">
		<Image Name="Splash" X="0" Y="0" Visible="no" ImageFile="splash2" Height="350" Width="180" HideWhenDisabled="yes"/>
		<Text X="200" Y="20" Width="-11" Height="30" FontId="2" DisablePrefix="yes">#(loc.ModifyHeader)</Text>
		<Button Name="RepairButton" X="200" Y="150" Width="100" Height="23" TabStop="yes" FontId="0">#(loc.ModifyRepairButton)</Button>
		<Checkbox Name="RemoveAllDataFilesCheckbox" X="310" Y="125" Width="250" Height="17" TabStop="yes" FontId="3" HideWhenDisabled="yes">#(loc.FullDeleteOption)</Checkbox>
		<Button Name="UninstallButton" X="200" Y="125" Width="100" Height="23" TabStop="yes" FontId="0">#(loc.ModifyUninstallButton)</Button>
		<Button Name="ModifyCancelButton" X="-11" Y="-11" Width="100" Height="23" TabStop="yes" FontId="0">#(loc.ModifyCloseButton)</Button>
	</Page>
	<Page Name="Success">
		<Image Name="Splash" X="0" Y="0" Visible="no" ImageFile="splash2" Height="350" Width="180" HideWhenDisabled="yes"/>
		<Text Name="SuccessHeader" X="200" Y="20"  Width="-11" Height="60" FontId="2" HideWhenDisabled="yes" DisablePrefix="yes">#(loc.SuccessHeader)</Text>
		<Text Name="SuccessInstallHeader" X="200" Y="20" Width="-11" Height="60" FontId="2" HideWhenDisabled="yes" DisablePrefix="yes">#(loc.SuccessInstallHeader)</Text>
		<Text Name="SuccessRepairHeader" X="200" Y="20" Width="-11" Height="30" FontId="2" HideWhenDisabled="yes" DisablePrefix="yes">#(loc.SuccessRepairHeader)</Text>
		<Text Name="SuccessUninstallHeader" X="200" Y="20" Width="-11" Height="30" FontId="2" HideWhenDisabled="yes" DisablePrefix="yes">#(loc.SuccessUninstallHeader)</Text>
		<Button Name="LaunchButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.SuccessLaunchButton)</Button>
		<Text Name="SuccessRestartText" X="-11" Y="-51" Width="400" Height="34" FontId="3" HideWhenDisabled="yes" DisablePrefix="yes">#(loc.SuccessRestartText)</Text>
		<Button Name="SuccessRestartButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.SuccessRestartButton)</Button>
		<Button Name="SuccessCancelButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.SuccessCloseButton)</Button>
	</Page>
	<Page Name="Failure">
		<Image Name="Splash" X="0" Y="0" Visible="no"  ImageFile="splash2" Height="350" Width="180" HideWhenDisabled="yes"/>
		<Text Name="FailureHeader" X="200" Y="20" Width="-11" Height="30" FontId="2" HideWhenDisabled="yes" DisablePrefix="yes">#(loc.FailureHeader)</Text>
		<Text Name="FailureInstallHeader" X="200" Y="20" Width="-11" Height="30" FontId="2" HideWhenDisabled="yes" DisablePrefix="yes">#(loc.FailureInstallHeader)</Text>
		<Text Name="FailureUninstallHeader" X="200" Y="20" Width="-11" Height="30" FontId="2" HideWhenDisabled="yes" DisablePrefix="yes">#(loc.FailureUninstallHeader)</Text>
		<Text Name="FailureRepairHeader" X="200" Y="20" Width="-11" Height="30" FontId="2" HideWhenDisabled="yes" DisablePrefix="yes">#(loc.FailureRepairHeader)</Text>
		<Hypertext Name="FailureLogFileLink" X="200" Y="121" Width="-11" Height="42" FontId="3" TabStop="yes" HideWhenDisabled="yes">#(loc.FailureHyperlinkLogText)</Hypertext>
		<Hypertext Name="FailureMessageText" X="222" Y="163" Width="-11" Height="51" FontId="3" TabStop="yes" HideWhenDisabled="yes" />
		<Text Name="FailureRestartText" X="-11" Y="-51" Width="400" Height="34" FontId="3" HideWhenDisabled="yes" DisablePrefix="yes">#(loc.FailureRestartText)</Text>
		<Button Name="FailureRestartButton" X="-91" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0" HideWhenDisabled="yes">#(loc.FailureRestartButton)</Button>
		<Button Name="FailureCloseButton" X="-11" Y="-11" Width="75" Height="23" TabStop="yes" FontId="0">#(loc.FailureCloseButton)</Button>
	</Page>
</Theme>

Build was fine and no errors appear, but my ui is empty

My Bundle.wxs part with customtheme.xml reference

		<BootstrapperApplication>
			<bal:WixStandardBootstrapperApplication  
				LicenseFile="Assets\License.rtf" 
				ThemeFile="Assets\customtheme.xml"
				LogoFile="Assets\UI\icon.ico"
				LocalizationFile="1033\customtheme.wxl" 
				Theme="rtfLicense" />
			<Payload 
				Name="1033\customtheme.wxl" 
				SourceFile="1033\customtheme.wxl" />
			<Payload 
				Id="splash2" 
				Name="splash2" 
				SourceFile="Assets\UI\splash2.png" />
		</BootstrapperApplication>

How to fix this? Or at least how to find out the root of a problem?
When i turn off this theme, basic rtfLicense ui is shown and there is no problem, so it seems to be custometheme.xml problem