Calling number not showing when you allocate to end-user within Teams admin center

Issue/ Scenario: When you attempt to go allocate the phone number to the end-user in the Teams admin center, on the assign/ unassign page, you get an spinning wheel as shown below:

Resolution: Unassign and reassign all the respective licenses from the affected user account Licenses and Apps section within the Microsoft 365 admin center and wait for 2 hours to get the number assigned and appear in the GUI.