That might be fixed now, I had the same issue on Connect a short while ago, and it's working now. I'm just waiting for Sync to come out for Lemmy.

Not all instances are going to be equal in terms of things like stability and uptime. It's going to be unfair and frustrating to users who might randomly end up on a bad instance. It might work if it only chose along the top x instances or something, to ensure a bit of reliability for new users.