I keep encountering this bug when building a Sandbox or Release Preview, users who had access on prod in the SB/RP show this: “This user has different email addresses to login into the system and receive notifications. Please update this record with the email address, you want to be used as a login name and notifications.” Even when their email is the same. Fix seems to be to remove login access and add it back in (with roles) again. That’s not practical for hundreds of users…