I feel like it's a motherboard specific issue. But if that's the case, I don't know what the patch would be (or if there even would be one). I had similar issues when trying to get UEFI booting working for my P9D WS (UEFI booting I never ended up getting working for the P9D WS). I even went to the lengths of using a different system's drive that had the legacy bootloader installed and it wouldn't boot from that one either. I've tried modifying the Terminal commands in the video to get legacy booting working for my Z87-WS (for Clover for GUID OS drives), but I haven't had luck. I haven't seen other posts in relation to this issue as well. I even tried copying some of the files on the EFI partition to the OS drive's Mac partition in hopes that it would read from there -as how I've seen legacy booting store files.