I just noticed that when I log in as non-admin on an SS3.0 site, the many UserForm submissions aren't visible. The Submissions tab shows "View X-Y of ZZ" indicating that the submissions are there, just no rows. (I can see all submissions when I log in as admin)
The user has most viewing and editing permissions and can access all other pages with has_many and many_many DataObject relations, just not UserForm submissions.
Any idea what permissions are necessary?