SpamSnake SpamAssassin Scoring Stops - SOLVED
I think I finally figured out what was happening.
Since I hadn't set up the sa-learn script properly when I originally built the Spamsnake, I hadn't actually run a force-expire or sync in about 18 months. When I fixed the script so it would actually run, there were hundreds of thousands of tokens to sync and it was just too many for the system to handle, causing it to timeout.
I ended up running a --clean on the db and starting over. After doing that, sa-learn would actually finish and messages continue to be scored.