I can't help much with firmware issues, I found that so many computers and BIOS are different, it's hard to keep track. I do have one suggestion. Go in Commander's terminal and "Custom command", then select ASF and PXE boot. I want you to try booting to PXE using that menu instead, if it works, just before typing this mail I unblocked the SOL feature in that dialog and it should allow you to perform a PXE boot with BIOS redirection. Just check that it solves your problem without redirection and I will issue a new release so you can do SOL redirection.
Ylian (Intel AMT Blog)