Epic Games - OS suddendly not supported anymore

Hi guys,
I downloaded Rise of Tomb Raider (20 Year Celebration) a few days ago on Epic Games. I already played ~3h and wanted to play some more today. Now the launcher suddendly says "Operating System not supported" for whatever reason. Im on a upper-middle class gaming pc with windows 10...
Any ideas what the heck is going on??

I tried to verify the game files and hoped it will fix it but it didnt. Thats why the logo has a gray part.

// EDIT:
Okay whats funny: Shadow of the Tomb Raider andd Tomb Raider GOTY Edition are now marked too as "operating system unsupported". They are not installed but I already played them on this same machine. WTF

// EDIT 2:
I can still start it via steam if I add the game files as "non-steam game". Its probably enough if I just start the game via the .exe too.... But my save games are not showing up..