I have the exact same issue. Ever since v4.1.1.5849914 ("Patch #7"), they've been forcing mod checks on multiplayer games, and it has been resulting in false positives. However, we eventually figured out that we could "unlock" the greyed-out "Play Game" button by un-ticking and then re-ticking all the false "mod issues". I reported this to Larian, and asked them specifically to under no circumstances break the "workaround" unless they could give us a way to ignore false positives.
Then v4.1.1.5970269 ("Hotfix" #27) came, and they did the exact opposite. Now we still get the false positives "Mod Issues" screen, but the workaround has been "fixed", and instead of tick-boxes we get endlessly spinning loading wheels, and - for whatever reason - an entire screen repeating "GustavDev" as an unofficial mod.
