Major Description
One issue noticed was that during initial sync a deadlock was detected while updating x_portal_user table which caused the initial sync failure. The subsequent syncs should have been successful, but because of a missing error case check during update of this user, subsequent syncs are also failing.
From the logs, I noticed that the initial DB deadlock happened for a service user. This user is being created by usersync during which I also see service creation request which also creates the service user if doesn't exist.