Mount error 19 in hyper-v

[kingrazor]

OS: Windows Server 2016 with Hyper-V
pfSense version: 2.4.3
Error: Mounting from cd9660:/dev/iso9660/PFSENSE failed with error 19.

I'm following the exact same steps I followed yesterday when I created a pfSense VM in Hyper-V Server (Hyper-V on bare metal). I was using a gen 2 VM with dynamic ram and a 40GB dynamic expanding disk. Everything worked fine.

Today I tried the same thing and got the above error. I tried using static RAM since a few people have had issues with dynamic RAM, but that made no difference.

The only difference is that I'm using a full install of Server 2016 instead of just the hypervisor. Any ideas?

EDIT: Trying a 1st generation VM worked. Not sure why a gen 2 worked yesterday and not today. Still interested in any thoughts anyone has, but I'm up and running.