BMD's RL8.6 Image won't boot?

I know that this is probably more of a BMD question than an RL question. Still, I am crossing my fingers that someone here can help while I wait for BMD to respond to my support ticket.

So Blackmagic Design hosts an RL8.6 image that has everything I’d need to run DaVinci Resolve Studio, but for some reason I cannot make a bootable USB version. I have tried balenaEtcher and Fedora’s utility to make a bootable drive, which has worked in the past. Hell, I’m currently running Fedora 43 on one drive and I can get the official RL8.10 ISO to boot just fine. I feel like I’m doing everything right when it comes to creating bootable RL media.

[EDIT] I should say: this problem manifests as not even being presented with the option to boot BMD’s RL8.6 image in the stock Apple bootpicker.

Anyone have any hunches? Maybe I am burying the lede here by not mentioning that I am trying to get this up and running on a 2010-2012 MacPro(5,1), but considering that I didn’t have any issues with the official 8.10 image I want to believe that this is something I should be able to sort out.

Anyway, here’re my machine’s specs in case that’s helpful:

MacPro5,1
(2x) Xeon E5620
Radeon RX580 8GB
96GB RAM
2TB NVMe (OCLP’d MacOS 12 Monterey)
1TB SATA SSD (Fedora43)
512GB SATA SSD (Blank)

Okay well, burning it to DVD at least gives me the option to boot this image but this is as far as I get.