First is since this is a upgrade. There were some bugs on older versions. I can't recall but it had to do with group assignments.
So I would select say one moderator and go through their settings.
Making sure they are in fact a member of the moderator group.
Using group management in the ubb control panel as well as member management to see what groups they belong to.
Just because they are listed as a moderator of a forum does not mean something is not amiss.
So even if the user looks correct then re-save the info to rewrite to the database.
Then I would goto forum permissions.
Same thing.
I know you stated that you have moderators set to a 1 but that was somewhat meaningless.
There are several settings.
Can see forum. Can read topics ,Can create new tropics. for starters.
So if you have them able to Can read Topics but can't view the forum then they can't see the forum.
So more details are needed.
I am not being curt with you but more details are needed to resolve your issue.
