The cause is unclear to me, but the processes that manage incoming and outgoing federation were "stuck" until I manually intervened. It's running now. I'm adding to my to-do list for after my job ends in 10 days to implement some sort of detection and hopefully automated restart for when this happens again.
Interesting choice over there to close the issue so quickly rather than asking for more info, although you didn't give them much to go on.
I wonder what was the resolution of the previous problem that frequently caused this sort of thing? Was the error handling improved such that we might reasonably expect the processing to keep going when it hits something it doesn't like, or was it just a quick fix for the one specific thing that happened to be breaking it at the time? Did that one make it to the github tracker?
That GitHub tracker is for problems with mbin code, not with instances running Mbin software. The problem that Fedia experienced is very likely caused by a bug of some sort in mbin (or something that Mbin is depending on), but we don’t know for sure what it is yet. Once I’m unemployed in a week, I hope to have more time to debug issues like this and get them resolved.