It took some heavy duty searching - but it seems that this is currently a Surface Pro Win 10 thing.

I recently replaced my SP 4 under warranty and the refurbished system came from the factory that...

My Surface Pro 4 (Win10 X64 Vrs 1703) is confused about Bitlocker
Disk Management indicates that the C: drive is "236.38 GB NTFS (BitLocker Encrypted)"
But Control Panel>System and...