Thank you for your reply. Alright, I just changed the disable_vga=1 to vga=none and rebooted the host.
~$ sudo cat /etc/modprobe.d/vfio.conf
options vfio-pci ids=1002:677b,1002:aa98 vga=none
Also, yes, after update-initramfs -u I rebooted the host (and with it the guests then), yesterday...