How do I determine which calendar entry is breaking my Android calendar sync?
I know it's typically frowned upon to answer your own question, but I have. This was a total PEBKAC. I use a different calendar app than the default, so I disabled the pre-installed Samsung calendar in the Application settings in order to stop it appearing in my application list. This is fine and doesn't affect anything, but I apparently got a little trigger happy and also quite stupidly disabled the Calendar Storage process. Yeah, that'll mess up calendar sync something fierce.