I define a device mapping in the admin console and later edit that mapping and change the username attribute because the owner of the phone device has changed.
A phone user with the new username is added to the phoneuser table but the record in phonedevice is not updated nor is the user with the old username deleted from phoneuser.
So I have an unmapped phoneuser that is indicated in the title on the admin console (Total Users: 2) but not shown in the mapping table below.
Either fix the update or make the username attribute imutable so the admin has to delete / create the record if the user of a device changes.
Just remove the old mapping and create a new one. The old phoneuser is removed in that case and both title (now: Total Users: 1) and table are correct again.