Unable to add member to workspace

[JasonG-BI]

I am unable to add a certain user to an app workspace.  I select the user as an admin or member but when i save this and return to the access area the drop down box is blanked out. This is user the old workspace version. i have been able to successfully add them to a workspace in the new environment. 

the user is a pro user and we are on a premium capacity

Thanks

Jason

[Wolfiz]

Hello

Does the user is well define on your azure active directory ? Have you check ? 

Sometimes the typo may change