From what I've seen on other posts about this, it's simply a current bug in the system. If it shows Subscribe Pending, you're subscribed successfully, that button just still shows pending even though it's working as it should. And you'll only see this on subs on other federated instances, not on your own.

It's a known bug. Likely you're subscribed.

I've seen some comments that this is a known bug, and you are actually subscribed to those subs. In some cases I had luck with unsubscribing (click the [subscribe pending] box) and then trying to subscribe again, in other cases that warning still won't go away but I'm definitely getting stories in from feed from them.

it's a visual bug, the community posts will still show up in your subscription feed

@Cloak@lemmy.ml this might need to be a sidebar FAQ.

I've got the same. But posts from those communities are still showing so just seems to be a visual bug