404 errors on multisite install

Hosting with 1and1
two sites on same account
Both set up as Wordpress multisite
Subfolder installs
Both are relatively new, content being created and added
preview-education works fine
preview-classes shows 404 errors on most pages and admin
permalinks are set the same
remove /blog/slug is used

Any ideas how to get preview-classes working?
I had originally tried to set them both up as buddypress sites. Buddypress caused errors and was deactivated. BP installed pages remain.