Possible Issue: Domain Lock
A common reason for a failure to upload a user comes from trying to upload a user with a different domain name when Domain Lock is enabled.
You can only add users from the same domain that you signed up with. If you suspect this is wrong, please contact support.
Solution: Contact support through the Messenger to have domain lock disabled on your account.
(Note: If you are an MSP, you can enable or disable Domain Lock for customers through uService. If your account is under a distributor, you can contact the distributor to enable or disable Domain Lock on your own account.)