Zoom phone user losing assigned DID

[chdz2024]

I have had to reassign a Zoom DID to a Zoom Users (Pro License) twice in the past four weeks. The DID seems to disassociate from the user. All the system parameters are the same as the other users in this group and have been double-checked. Any suggestion of why this user is dropping the assigned DID and a possible solution would be greatly appreciated.