Migrate UWP App to MAUI Windows: Error after update with MSIX

I currently have a Xamarin Forms UWP App in the Microsoft Store.
In the next months I want to update it to MAUI.
For testing purposes and ensuring that all stored data are still available within the app, I want to simulate the Update of the Xamarin Forms app to MAUI with side loading for Windows.

After installing the MAUI-msix-Update, an error appears:

Is this a general problem or do I have a specific issue in my manifest?
Sample app:
https://github.com/reinhardlackner/SampleUpdateMauiApp

• Debugging is working correctly (I can start the UWP-App "SampleUpdateApp.UWP" in Debug mode... and after closing it I can start the MAUI-App "SampleNewUpdatedApp") - and the saved click-data from the UWP app are shown in the MAUI app:
  

   

• Sideloading-Update does not work:
  a) SampleUpdateApp.UWP - Right click => Publish... Sideloading
  Use test certificate
  
  
  Install UWP app appxbundle-file
  
  

  App opens => OK
  
  

  

  b) Install MAUI App as Update
  SampleNewUpdatedApp - Right click => Publish... Sideloading
  Use same certificate
  Create MSIX x86 publishing profile and version is 1.0.1 (update of Xamarin 1.0.0)

  

  Start created msix-Package and click on Update:

  

  Error message is shown:

  

  App installation failed with error message: Deployment Add operation with target volume C: on Package E965F79B-76C7-47E0-8308-4A503105EDE0_1.0.1.0_x86__ab06nvn9z6x6m from: (SampleNewUpdatedApp_1.0.1.0_x86.msix) failed with error 0x80073CF3. See http://go.microsoft.com/fwlink/?LinkId=235160 for help diagnosing app deployment issues. (0x80073cf3)

• If the Xamarin app was not installed before, the MAUI App can be installed correctly:

  
  
  
• Does anybody have an idea why the update installation is not possible?
  I assume it could be related with the Manifest-File...
  Manifest UWP: 
  https://github.com/reinhardlackner/SampleUpdateMauiApp/blob/master/SampleUpdateApp.UWP/Package.appxmanifest
  Manifest MAUI:
  https://github.com/reinhardlackner/SampleUpdateMauiApp/blob/master/SampleNewUpdatedApp/Platforms/Windows/Package.appxmanifest