Mailing labels doesn't work for address type 'main'

We are getting unexpected results when attempting action "Mailing Labels - print". It appears to work as desired if address type "Primary" or "Home" is selected, however, when you select type "Main", you get either 1 complete label only (4.7.5), or labels with only the contact names but all address info missing, in some instances a blank PDF) (4.7.7, and on the 4.7.8 demo site).

I have not tested options "Billing", "Other", or "Work", but type "Home" and "Primary" appear to work correctly (show full address info, number of labels matches results returned).