SOLVED in 1.9.0.900 RC1
Hi @Mark Ingram
As I mentioned before
Neither Designer or Photo beta starts from and with build 885 (the prior beta worked)
Publisher beta 887 start normally though
Repairing .net framework did not work
Installing .net runtime 5.0 did work
Reinstalling Designer + Photo beta (deleted everything in %appdata% related to them) didn't work
Uninstalled FastPictureViewer because of this thread - didn't work
The latest release builds of all three run normally
Further I am running Windows 10 Enterprise on a freshly updates 20H2 with no knows issues whatsoever, everything runs fine and no error check-ins tools - for example Microsofts .NET checker - report any errors. Only these two apps malfunction
The two apps just terminates immediately with the error message I sent you; cant' reset settings with CTRL.
Build 876 of Designer and Photo works.
So... Interesting that Publisher 887 works - and Photo/Designer 885 does not.