Hey there!
Sorry to bring back an old thread, but I just upgraded from 6.9.2 to 6.11.5 and am having this exact issue. Were you able to figure out what was wrong?
thx!
EDIT/UPDATE: To answer my own question, I was able to resolve my issue by changing the following lines in my xml config.
I changed this:
<loader readonly='yes' type='pflash'>/usr/share/qemu/ovmf-x64/OVMF_CODE-pure-efi.fd</loader>
<nvram>/etc/libvirt/qemu/nvram/18c0c596-a5fe-45f5-ae00-6a86497a4b3f_VARS-pure-efi.fd</nvram>
to:
<loader readonly='yes' type='pflash'>/mnt/user/domains/MacinaboxCatalina/ovmf/OVMF_CODE.fd</loader>
<nvram>/mnt/user/domains/MacinaboxCatalina/ovmf/OVMF_VARS.fd</nvram>
Hope this helps someone.