Updating to VS 2022 broke my Tool Window (InvalidCastException)

[mhershberg]

I tried updating a custom extension of mine to VS 2022 and ran into a problem I don't know how to solve. The extension has a tool window, derived from BaseToolWindow. When I try to display it by calling ShowAsync() in response to a menu command the code it throws an exception: "Exception thrown: 'System.InvalidCastException' in mscorlib.dll"

I've followed the examples in the Community Toolkit site and I'm not sure what's wrong. The exception doesn't stop execution of Visual Studio or break into the debugger so I have no idea how to debug this.

I can put a breakpoint on the ShowAsync() call but stepping into or over just resumes execution and logs the exception.

Please help!