This afternoon I was playing on 12.0.77 continuing my game from yesterday, saved it and then booted the game back up after dinner without even turning off the computer in between.
and not only did it no longer show my savegames - it only showed 3 from last week (my "real" save game files are still in the folder on the disc) but also opening up the "load game" menu took more than 30 seconds when it's normally max 1s and I can also no longer click on "new game -> scenario / tutorial / accomplishments / challenge game" (clicking on "custom game" freezes the game. loading up the 3 savegame-files seemed to work but didn't resolve the issue. (it also still recognizes that I own all DLCs and stuff like that)
I uninstalled and re-installed (now up to 12.0.81) thinking there might have been a patch issue or so, but the behaviour didnt change.
this might or might not be related, but I found TWO folders in my install location:

the first one contains the game, the second one a folder "WebView2" with about 10mb worth of various files.
I'm playing on a win10-machine but dont think that should really matter since the game has so far usually run smoothly on this very computer.
i vaguely remember having this or a similar issue in the past but unfortunately dont remember what resolved it, hope you can help me here by pointing me in the right direction