Normally it's pretty quick, but sometimes it can take a few minutes. Other times it seems to get stuck. If you cycle it one or more times it may hook up right away. Doesn't matter though, you still see a community's posts even though it says pending, really just an indication issue. They should get it working better pretty quick as Lemmy develops.
okie dokie, thanx! I was just wondering since I just read something about beehaw communities shadow banning if I sign up for certain other communities and was wondering if that had something to do with it. Reference: https://lemm.ee/post/547600
Due to the nature of Federation, don't hesitate to make accounts on different instances as needed to access that instance's content. I reckon a number of people have accounts on Beehaw and accounts elsewhere.
Beehaw does tend to block other instances for content, but that's not common. Most instances only block for abuse. If you want to make sure you can talk to a community on another instance, check the Instances link bottom of page. It shows you what's linked and what's blocked. You need to do that both on your local instance and instance hosting your community of interest.
Aa far as I know, it's more of a visual glitch. I still have a "subscribe pending" for some communities, but I'm otherwise subscribed to the community.
I believe that your subscriptions are pending if the community you're subscribing to belongs to another Lemmy instance. I'm guessing that a moderator might need to approve your membership. But I could be entirely wrong!