I expect that's the problem - certainly MDE only encrypts drive with letters regardless so we would not expect it to be encrypted without one.
Our Dynamic, GPT disk is one physical disk not spanning others. I would think this would encrypt the whole disk. Isn't DE whole disk encryption? Or does it only encrypt the logical piece of the disk? Looking at the log file I do not see anything that states it could not see a drive.
lots of reasons - dynamic disks are handled very differently by the OS than basic disks and are pretty much impossble to recover outside the OS. They have never been supported.