Hi
It sounds like you may have switched on VPP - can you remember having done this?
If so it might need further configuration.
Have a look at Apps > Catalog > More > Apple VPP Licences
Here's some documentation:
https://www.ibm.com/docs/en/maas360?topic=overview-apple-vpp-managed-license-integration-guide
Let us know how you get on.
Best
------------------------------
Eamonn O'Mahony
Technical Client Success Manager
IBM Security
Dublin, Ireland
------------------------------