This is the bug report for FreeDOS, not Hyper-V. I at least want to see FreeDOS able to be run on Hyper-V, even if they don't choose to support FreeDOS. I have been able to replicate booting through CD as working, so it appears that there's some difference between the two.
Given it doesn't allow the file as being too large I have uploaded it to my site: https://arenlor.com/Hyper-V.7z that is an archive of the virtual machine and HDD.
It still fails at the same location.
JEMM in 1.3 RC4 on Hyper-V from Windows 10 Pro fails to boot