There is quite a hoo-hah on the Affinity Forums around its chose of installing version 2.0 Affinity products as .msix files.
Basically, linking Photo Editing > Editing Bitmaps now requires a default path:
Code:
C:\Users\[USERNAME]\AppData\Local\Microsoft\WindowsApps\AffinityPhoto2.exe
with no spaces!

The trick in XPro+ (probably other XDAs too) is to copy or key in the above including your username instead without pressing the Enter key and then click Apply.

Took ages to work out.

Acorn