On my HP xw9400, when I boot from a stick with FreeBSD-12.1-RELEASE-amd64, I get a list as follows
BIOS drive C: is disk0
BIOS drive H: is disk5
Then it hangs at the vertical bar. Why might this be?
Wrong bios settings or a BIOS that is incompatible with the FreeBSD boot loader somehow. I would try to mess with settings for usb in BIOS and see if that helps.
also, check if your machine has the newest version of the bios, if not - upgrade. Perhaps it helps.