Re: 404 for groups
You are viewing the groups directory? The one labeled ‘Groups Directory’ with the ‘abcdef..’ and the search box. If the directory is displaying but you get 404 for the title. Or ‘not found’ as the title. Something like that then that’s fixable easy.
The 404 result for directories is a known issue. The workaround is to create a blank page with the slug ‘groups’ in wpmu. Do the same for the other directories. You’ll wind up with three placeholder pages.
Credit to wardeh again for the solution.