Run the following command on the UPN accounts to convert them from (your domain).com to (your domain).onmicrosoft.com, and back again. This resynchronized them with the federated settings and synchronized Microsoft's value behind the scenes:
Set-MsolUserPrincipalName -UserPrincipalName (username)@(your domain).com -NewUserPrincipalName (username)@(your domain).onmicrosoft.com
Set-MsolUserPrincipalName -UserPrincipalName (username)@(your domain).onmicrosoft.com -NewUserPrincipalName (username)@(your domain).com
Questions?
If you have any questions or need some help, we would be happy to assist. Open a case at help.scorpionsoft.com or send an email to support@scorpionsoft.com.