This issue only occurs for customers who have been on GTS Online for many years, and who have been migrated to a newer server.
Enable Advanced Features
Launch Active Directory Users and Computers from any of the AD Domain Controllers. Click on View > Advanced Features if not already enabled.
View user Properties
Open the OU of the user you are checking. Right-click the user account and select Properties. Click on the Attribute Editor tab. If there is no Attribute Editor tab, see the Enable Advanced Features section above.
Clear the userParameters Attribute
Scroll down through the list of Attributes and locate userParameters. Click the Edit button.
Click the Clear button, and then click OK to save your changes. Close out of the user account.