I have also run into this issue, but only for a couple of users at this point. My workaround has been to create a local account that the user can log into and back out of, then they can log in to their own account. I haven't been able to pinpoint a cause or fix at this point, however. I am looking into the AD accounts of the couple of users it is affecting, as I built a new machine for one user and ran into the same problem on the second machine as well.
The users can manually enable FV by going in to system preferences>security>FV and turning on. It will then ask to escrow key to mdm.
Removing then repushing the profile also works. Are machines are not bound. We’re using local account with Enterprise Connect.
Annoying that the automation of enabling FV has stopped working in 10.13.3
It was an issue with profile collision from the 10.12 FV profile. Adjusted the scope and works as expected...