Just an update on the easy group transfer issue. It certainly seems like I'm running up against some sort of rate limit for accepting invites for the transfer groups.io account. I seem to be able to accept about 17 invites and then it starts erroring out. I've tried using a VPN to see if it's just tied to my IP address, but it's apparently tied to the account. The limit appears to be in effect for more than 24 hours. I currently have a backlog of 15 invites waiting to be accepted.
I'll be putting a notice on the easy group transfer page explaining that there may be a delay in accepting invites.