After making the Howto Azure Backup blogpost, I could make it work with Windows 8.1 Enterprise and every attempt reported Operation Failed (0x1D4C2).
If it was Windows Professional, it could be a feature only for Enterprise, like Direct Access. But Azure Backup works with all versions of Windows 7, 8, 8.1 and 10.
I then asked my good friend Bing an Google, where I found the Developer Network Community Forum and Microsoft say the issue is known and they are investigating it.
Qoute: Azure agent is not able to prune BitLocker file during backup.
Sadly, no ETA on a fix at the time: January 28th, 2015.
Until then, do you want Backup Security for human errors or Device Security for preventing theft?