UEFI based VM refuses to boot

Not sure why but this post is a life saver (hours, at the very least, will be saved)

Essentially. If the boot fails you are likely to end up in the UEFI shell. type exit

Go to 'Boot Maintenance Manager'
Go to 'Boot Option'
Go to 'Add Boot Option'
Press enter on the 'PciRoot' volume
Select EFI and press enter
Select the folder of your OS (in my case it was 'debian') and press enter
Select the EFI file (in my case it was shimx64.efi) and press enter
Change the boot order (use + to move up the entry) and also here F10 save (y) esc esc reset

full life saver:https://forum.proxmox.com/threads/how-to-boot-grubx64-efi-after-import-from-hyper-v.55429/#post-255178