I have the same problem. Hidden and Private forums are not available for any users. (got 404) If I make them public(as a test) they are available.
This happen after update.
UPDATE: “Repair Forums” -> “Remap existing users to default forum roles” solved the problem.
After update my forum styling got corrupted. ‘width’ parameter on posts seems to be not correctly set.
Anyone have an idea where this parameter is set?
Using Suffusion theme.
O