user not registered in users and groups

It looks like I have a user that did not select a Mobile account on the PC at setup.

They can login via the Domain and they can run MOST of the local programs with no issues. (Adobe Illustrator excluded)

However this device is about to go off site and they need to be able to log-on locally.

When I logon as a Domain Admin or Local Admin I do not see the account in Users & Groups.

So I can't manage the account in any way.

Any suggestions?

Many Thanks in advance.