Had the same issue, try to unsubscribe/resubscribe a few times and it might go through. Worked for me. Took a few attempts though.

Yeah - I think that is happening to me to

I have the same issue, lemmy.ml was quite overloaded, so they did add some protections to make it faster gain. I guess it is related to those settings.

Occasionally I can redo the subscribe and it will work instantly. Not a consistent thing, but every once in a while I went through my subscribed communities and redid the pending ones until I got them all subscribed