Just a note here -- I've had ongoing issues too that cache/cooke clears do NOT resolve.

In my situation, it breaks when there are >100 pending transactions to auto match.

If I get the pending transaction count to lower than 100 (by doing some bulk manual matching) then it eventually starts working again. Give that a try if you have a lot of pending matches.

Super annoying -- and this has been going on for over a year!