This has happened to me as well. The most common reason I was given was that the enterprise licencing provision file has been damaged.
You can however easily sort this. In the Creative Cloud Packager, you'll notice there's an option to create a serialisation file. Simply follow the prompts, entering your enterprise serial number.
On both Windows and Mac, it'll create a folder with an Adobe Serialisation (.exe for Windows, terminal script for Mac). Running those re-provisions the serial number.
For Windows, I created a small SCCM 2012 package using the folder the serialisation is in, with the program being the serialisation exe - and deployed that as needed. Worked a treat without hassle. Mac users in the enterprise can use something like Casper to deploy that as required.