version 0.7.9 gives grub prompt on all OpenBSD guest installs

[fd0-nl]

I have tried to install all available openbsd versions (supported) and found out that all installs ended up the same with a prompt inside grub

the generated grub.cfg file is

# cat /iohyve/openbsd58/grub.cfg 
kopenbsd -h com0 (cd0)/5.8/amd64/bsd.rd
boot
#

and the corresponding device.map is:

# cat /iohyve/openbsd58/device.map 
(hd0) /dev/zvol/pool1/iohyve/openbsd58/disk0
(cd0) /iohyve/ISO/iistall58.iso/iistall58.iso
#

I have tried with all available and supported openbsd versions, even with unsupported versions up to 6.3
All give the same.

The command that gets started is

grub-bhyve -m /iohyve/openbsd58/device.map -r host -d /iohyve/openbsd58 -c /dev/nmdm1A -M 512M ioh-openbsd58
I have no idea where is went wrong, especially since i followed the link on the wiki at "Other BSDs"

Any hint would be appreciated.
Machine running FreeBSD-11.2-RELEASE