Not able to install VPP apps on iOS
I'm glad you were able to resolve the issue.
Apple throttles the Apple VPP services if a MobiControl instance is too chatty with Apple VPP services. Normally, you'll see this reason when trying to Refresh the VPP token or in the Device Logs for a device that tried to install an app.
We could resolve the problem.
We saw, that in dbo.Settings there was a timestamp set for IosVppServiceUnavailableRetryAfter.
We changed the value to a date in the past. After that, the apps installed properly on the devices.