Whenever I add a new overlay, it'll show up in the options but won't appear after I exit the mod selection menu in the game. I have no idea how to fix this or if it is even fixable.
Is there anyone here who does know of a way for this to work?

Bump.
I have the exact same issue on mac. I can find all the mods in overlays, but even though i chose them. It still says mods (0) when going back to the menu.

Mine too! pls help!

I'll take a look into this and fix it for the next update.

Can confirm there's an issue there on Mac, directory existence check is made erroneously without the full path failing a valid case. Will be fixed in the next version.