Hyper-V Enhanced Session Mode 'Intercept' Stopped Working

WIN 10 build 1809. Very strange problem. Hyper-V was working fine with enhanced sessions and then went south. Checked Hyper-v settings and both Server -- > Enhanced Session Mode Policy and User --> Enhanced Session Mode are checked. With new virtual machines there is no opportunity to set resolution, etc.
Turning off and on enhanced settings -- no joy. There are no files in the vmconnect directory that correspond to my present VMs, only one old one vmconnect.rdp.xxxxxxxxxx.
I need to change the video size for my existing vm's, but cannot. For a Linux VM I managed to change the video size by modifying the GRUB_CMDLINE_LINUX_DEFAULT in Linux.
Another important piece: I also use viboot under Macrium to create VMs from backups and it works perfectly:
the enhanced box pops up on every start to change parameters. Macrium uses Hyper as a back end.
Why isn't hyper-v creating vmconnect.rdp files for new VMs? What can I do to further troubleshoot this issue?

Uninstalled and reinstalled -- no change. Thanks for the suggestion.

Karl --
Thanks for your info about RDF config files not being created. But my problem still exists. The option to choose enhanced mode is greyed out and cannot be chosen. When creating a new VM, I am not presented with any extra connect options with vmconnect. It just goes straight to the VM.
I did see an old thread with a similar problem, but no solution was found. One of the config files in C:\Users\<user>\AppData\Roaming\Microsoft\Windows\Hyper-V\Client\1.0 has an entry for 'first run' set to 'false' but I don't think this has any impact? Also, there is a disk cleanup option in hyper-v that I haven't touched. Also, when I uninstalled Hyper-V I didn't delete the config directory or any configured switches, but I finally got all my existing VM's going again, but the enhanced mode for existing and new VMs is still greyed out.

One additional point: All my VM's are Generation 1; my computer is set up as MBR (not UEFI). When I use viboot under Macrium enhanced mode works perfectly. The settings pop up every time the VM is started.

Karl,Installed VMs are WIN XP, WIN 7, Limux Mint 19.1 Also have a VM created by Macrium viboot
My operating system is WIN 10 Pro currently running 1809. Hyper-V worked properly after installing 1809, and also works perfectly when creating a VM using viboot.

I just reread your previous comment -- the problem is my VMs are all old, EXCEPT the win10 PRO VM I created using viboot!!!

I guess this solves the issue??

Karl -
I edited my previous thread as you were commenting! I read your tutorial in the past but missed the part about WIN 8.1 or later Also I assume Linux 19.1 isn't a candidate for enhanced.
Thanks so much for your time and excellent input.
Cheers, Hank