Can you give more specific repro instructions? Just to make sure, you are running this on Windows, right? (Windows is requirement for GameWorks itself)
I just did fresh build for my 4.21-GameWorks and opened Soul: Cave with it. It worked fine in the editor without errors (I also opened all included maps with it just to make sure it’s not some specific level that triggers the error). It also worked fine when I packaged it with Shipping & 64-bit conf and ran the result in standalone so there’s not much I can do from my end unless you can give more specific repro case I’m afraid
edit: I originally opened Soul: Cave as a blueprint project. I now also tested Soul: City with c++ project as well but it works fine on my end too, all levels load up fine. Both tested on my 4.21.2 GameWorks branch.
Also, have you used the branch with or without WaveWorks? The branch I’m testing with now doesn’t have WaveWorks.