Issue appears to be caused when a Community Licence has been “Upgraded” to an Enterprise Licence.
The “Default Service” created initial for the Community Licence has the standard 2 Studio, 2 Attended and 1 UnAttended allocation.
The New Enterprise Licences show on the Licence Screen but there allocation DOES NOT automatically the information in the Service. As the Community licence needs to be renewed every 30 days, it generates this error which says nothing useful.
On the Service page, Edit the service. Change the licence allocation to reflect the licences in the Enterprise plan. Save the changes and the issue is resolved.