Microsoft has just updated the following KB Article:
Windows Phone 8.1 users can’t install apps on corporate-owned devices
Symptoms:
If your enterprise owns and distributes Windows Phone 8.1 devices for management by Intune or System Center Configuration Manager, information workers (IWs) may be blocked from device enrollment and application installation. This problem occurs if the devices were previously enrolled and then retired.
Full details at:
https://support.microsoft.com/en-us/kb/3045272