I believe this is an App Volumes related issue, we are not having this problem with full clone VMs that do not have App Volumes enabled on them. We are using the UIA + Profile template on all of our Windows 10 VMs, build 1607. What is happening is when users log in for the first time, some will get the Windows 10 welcome screen and it never completely logs in. In the Horizon console, their particular VM shows no username associated with it. We have to do a "reset" on the VM, then the next time they log in (we use linked clones, so it will pick a different VM in the pool), it works and the problem never comes back. I suspect this to be some sort of combination of Msft with AppVol Writable Volumes and the way windows initializes a new profile, but I have no idea what it would be. This doesn't happen to every new user (which are set up identially), maybe about 20% of the time.
Anybody else having this issue?