I am having the same issue. The regular Enable BitLocker step is failing and when I checked it was only 12% complete encrypting the drive. We have seen this quite a bit over the last 1-2 months, but just getting around to digging into this now. I have not been able to find an errors with the pre-provision step, only been able to find errors at the Enable BitLocker step.
I'm not sure if this is only happening on hardware that we are reimaging and not new stuff that's right out of the box. I am going to clear and disable the TPM in the BIOS on the machine that just failed and try again.
smsts.log
smsts-20140403-085522.log