I'm having the same problem - I've got the Windows Store version of Photo and Designer, and after the 1.9 update they both crash at the splash screen. I uninstalled Photo thinking it might have become corrupted, and now when I try to install it from the Windows store I get a Code: 0x80073D05 error.
I did some searching on this error code, and it seems to relate to licenses. This would make sense if the licensing got borked with this update, and might possibly explain the programs force-quitting at the splash screen, but it's just a theory.
Unfortunately, I cannot try the beta because I cannot install the Windows Store version, and that is required to use the beta. Any other ideas? I'd love to just use the Affinity store and installer - is there any way to transfer a Windows Store license over and get a product key?