" Posts from other instances are getting in, but no posts are getting out. "
Ahhh... okay, that is probably related to the problem them. :blobsad:
"But if they are already following me here, does that cause any issues?"
No, that shouldn't be a problem. I've sometimes followed people's new accounts before the transfer did it automatically, and it worked fine. By the way, the transfer requests are totally behind the scenes, most people won't even notice anything.