This happens when the iPad has become deprovisioned from Workspace ONE. Typically, the only way to resolve this issue is to wipe and re-enroll the iPad. Because it has lost its ability to communicate with Workspace ONE, you must wipe it manually from the iPad.
From the Home Screen, tap Settings, then General, then Reset, and then choose Erase All Content and Settings. Once the iPad reboots, it will automatically install the Hub app and it will have re-established its communication to Workspace ONE, so you will be able to re-enroll the iPad.
Occasionally, when the iPad is in this state, it will automatically begin a software update of several installed apps. You must wait until this software update completes before you can Erase All Content and Settings. The software update will complete faster if you connect the iPad to a Wi-Fi network.
If this doesn't resolve the issue, or if you do not see the option to Erase All Content and Settings in the Reset menu, then you will need to send an email to ipads@desalesmedia.org with the serial number and a description of the steps you have tried so far.