Problem with TinyCore Linux in Bhyve in TrueNas

I have a TrueNAS Core system running TrueNAS-13.0-U6.1.

I'm trying to install TinyCore Linux in a VM.  I've tried various
images, just repeated the experiment with the 17MB Core image from
http://tinycorelinux.net/downloads.html (sha256: e2d98595cf62133df71516602c12aa685c6b4da19db3068d150e4946415d0d86  Core-current.iso).

When I run through the configuration menu, generally taking the
defaults, in particular choosing UEFI boot, I end up at the UEFI shell
menu (in both VNC and the serial shell window).

Trying the UEFI-CSM boot setting I end up with "connected" in the
serial console window but nothing and no response to the keyboard.

Trying grub boot setting gets me a message from the UI that says:

    > [EFAULT] Unable to find boot devices for '1_tc' domain

I've booted Alpine Linux in UEFI mode w/out any issues.

Any suggestions for next steps?

Thanks,

g.