Came across this when trying to fix the same issue I was having with installing TrueNas.
After several changes the one that worked for me was to make the following change in BIOS:
Advanced>CSM Config>
Boot option Filter (UEFI & Legacy) <this is the default>
Storage = UEFI
Other PCI devices = UEFI
I then put my os drive in P0 then had the rest of my drives after that, but did did test this with TrueNas installed on a USB and had it in the internal header and it worked as well.
I should note that I have the F5-221, but BIOs version matches yours.
I hope this helps a little.
