We haven’t seen these issues on our hosting, or from any other self-hosters, so this is likely a problem specific to your server. We don’t have any relevant fixes in the pipeline.
From the symptoms, it sounds like Sidekiq (the background job processor) is not running correctly.
Do you see any recent errors when visiting /logs on your forum?
How does /sidekiq look? Does it show jobs being processed?
In a healthy state, the ‘enqueued’ number should be close to zero. I suspect if things have been stuck, your number is very high, and may take some time to process down to 0.
Sidekiq was (seemingly happily) running, but it seemed to be stuck since the update to 3.4 with about 1000 jobs queued. Since updates often do rebakes or async things, we didn’t really see that as something suspicious.
A restart of the process did the trick. I suspect the who’s online plugin might be the culprit but I’m not 100% sure.