1. Open a C++ application in Qt Creator.
   I used the shortcuts manual tests from qtbase\tests\manual\shortcuts\shortcuts.pro.
2. Configure it to use Qt 5.15.0 beta1 for UWP 64bit (MSVC 2019), Debug configuration.
3. Click the "Play" button in Creator's lower left corner.
   The application's window will show up but then close again. In Creator's "Application Output" view you can read something like:

   21:49:43: D:\Qt-05.07e\Qt5.15.0\5.15.0\winrt_x64_msvc2019\bin\winrtrunner.exe --device 0 --start --stop --wait 0 --profile appx D:/dev/src/qtbase/tests/manual/build-shortcuts-Qt_5_15_0_for_UWP_64bit_MSVC_2019-Debug/debug/shortcuts.exe
   qt.winrtrunner: Using the Appx profile.
   qt.winrtrunner: Package already installed.
   qt.winrtrunner: Failed to activate application: 0x8027025b "Die App wurde nicht gestartet."
   

Release builds and MSVC2015 are fine.