I seem to have found an easy solution. I had the same issue on my Windows 10 system. Initial solution was just to reinstall, from the full installer, version 30.1, just to see if I could the functionality of FreeFX back. This worked, and I decided I would just wait to see if there were any solutions before attempting to update OBS again at some point in the future. In the meantime I did some digging, and found other users having issues, different issues related to streaming, and that apparently the problem was the in-app updater. Supposedly it removed files that were necessary for OBS. I decided to try the update again to 30.2 using the full installer, and now I have it updated and FreeFX still working. I haven't put it through it's paces to make sure that everything is 100% fine, but at first glace, all seems fine, and the FreeFX filters are there. Perhaps it's not even necessary to reinstall 30.1 first. That's just the route I took because my intention was just to roll back. Also, I never ran any uninstall routines. I simply ran the full installer and let it install in the same directory over top of itself.