I solved this issue thanks to launching a live version of Linux (ended up using Mint for that) and updating the MOBO bios. ASRock boards will work with Proxmox, it just seems to take some black magic to get working in my case. I'm excited to start working on this stuff now at least! Thank you so much BobhWasatch for your suggestion with the live CD, and thank you Leesteken for doing everything you could to help me get to the bottom of this issue