I‘m aware of the current federation issues that might also be the reason for this issue but I noticed that while federation of posts from feddit.de works sometimes as well as posts and comments from other instances no comments from feddit.de are syncronised at all.
It might be better to ask there but as I do not have an account there I thougt I first ask here if this is already known. Does somebody else also have this problem?
Yep, I've had all kinds of issues posting comments from my feddit.de account.