I'm not sure how pervasive this is, but Maeve@kbin.earth's comments don't seem to have federated. I can only see 24 of them from 9 months ago, but when I go to kbin.earth I can see the user has over 3000.

I'm definitely not a federation expert, so there may be a good reason for this. I wanted to point it out in case it was part of a larger issue.