4.2 borks syncing (fixed)

2015-12-16: See update below.

The 4.2 update was supposed to be all about syncing. It worked just OK before (filters never synced) but now nothing syncs. The read marker is missing, and the unread count and position don’t sync between iPhone and iPad, or between iOS and OS X. I tried turning syncing off/on, resetting the cache, etc. It doesn’t sync ANYTHING now on multiple accounts. For example, the unread count on my iPhone says 7, the iPad says 2, and the Mac says 36.

RSMAC about Tweetbot 5 for Twitter, v4.2