Reaction like sync issues

I upgraded our site last week from 3.2.0.beta4-dev to 3.3.0.beta3. (Yesterday I updated to 3.3.0.beta5-dev)

All was fine until I enabled the reactions like sync setting (see image below). From that point on, the server appears to have been busy processing the reactions, and users are getting 502 errors and many requests are not being handled properly. Some threads aren’t marked as being read, they aren’t able to post randomly, etc.

Is there any way to see how far along the retroactive background process is so we know when this behavior will (hopefully) return to normal? Or any updates to handle this better? Or slow it down so it doesn’t impact site performance? Or is this unrelated and just a coincidence?

Also of note: the site has 2.4M posts and around 2M likes.

FYI @martin

Not sure if you ran across anything like this when enabling for the hosted sites?

Following up on this … is there any way to see the progress / remaining items in this?

I updated the ScheduledLikeSynchronizer to run every '0,30 4-10 * * *' (only overnioght) instead of every 1.hour (constantly) but it doesn’t appear to be working; is that cron notation available? I’m trying to let this continue to run, but not interfere with our user’s ability to use the site.