Learn Editor: Update mac-whatsnew.md

Author: j0shbregman

defender-endpoint/mac-whatsnew.md

@@ -44,6 +44,8 @@ To get the latest features, including preview capabilities (such as endpoint det
 
 ## Known issues
 
+- Starting with version 2506 (101.25062.0005), attempts to upgrade Microsoft Defender for Endpoint on macOS consistently failed.  To overcome this issue, there is a workaround that can be applied using an MDM such as Microsoft Intune or JAMF. 
+
 - Apple fixed an issue on macOS [Ventura upgrade](https://developer.apple.com/documentation/macos-release-notes/macos-13_1-release-notes) and macOS [Sonoma upgrade](https://developer.apple.com/documentation/macos-release-notes/macos-14-release-notes) with the latest OS update. The issue impacts Defender for Endpoint security extensions, and might result in losing Full Disk Access Authorization, impacting the ability of Defender for Endpoint to function properly.
 
 - In [macOS Sonoma 14.3.1](https://developer.apple.com/documentation/macos-release-notes/macos-14_3-release-notes), Apple made a change to the handling of Bluetooth devices that impacts Defender for Endpoint device control's ability to intercept and block access to Bluetooth devices.  At this time, the recommended mitigation is to use a version of macOS earlier than 14.3.1.