Workstation 15.5.5 - Hyper-V Docker Desktop and Ubuntu will not start inside Win10 VM (15.5.2 works)

Workstation 15.5.2 worked fine.

Upgraded to Workstation 15.5.5  - Hyper-V Docker Desktop and  Ubuntu will not start inside Win10 VM

Reinstalled 15.5.2, works fine.

Base machine Win10 Hyper-V disabled

VM

Win10 Hyper-V enabled

Linux based VMs inside the Win10 VM will not start:

--> Hyper-V Docker Desktop will not start

--> Hyper-V Ubuntu VM will not start

--> Hyper-V WinXP VM did start

What happens is that Hyper-V says that it is started, but It just sits at a black screen and uses a lot of CPU. Left for a hour and nothing ever happens. No errors or anything.