Sort option disappears

I just upgraded from 1.4 to 1.6 and now and then - we haven't figured out yet how this is triggered - the view's VotingAPI sort options disappear. The view itself is then left in an unfunctional state, generating no output, instead throwing an SQL error because of an empty ORDER BY: "ORDER BY DESC LIMIT 0"

Within the views UI we can see the sort widget, but is has no description.

We found out we can fix this for some time by editing the content type which uses the fivestar widget and save it without changes. After that the view resumes normal operation and the UI is fully functional again.

For some unknown reason it happened again after the first fix, without any changes made in between to the view or the content type.