This is a well-known bug, and I have read just about everything there is to find. It seems to occur in other games running on Unreal Engine too, but in XCOM 2 it happens so often that the game is simply not fun any more. It can happen whenever, but usually when in the base or returning to base.
Things I read about that might have worked for some and that I tried so far:
- disabling all DLCs: makes it better, but doesn't completely go away
- setting my swap file size manually to three times my RAM size (=3*16GB): doesn't help at all
- I don't have mods
- I have Windows 10 and a Geforce GTX 970 with latest drivers
Is there any remedy for these annoying crashes?