Bug Report: Hardware Accelerated Performance works maybe 40% of the time.
Cutting in Adobe Premiere 2018 12.1.2 using an iMac Pro 10 core, 128Gb ram, vega 64 16Gb.
You get an option for Hardeare Accelerated Encoding but limited to VBR 1 pass. It can be really fast (if it works) but I have found that it causes my entire system to shut down mid export and sometimes losing a lot of my progress on my timeline. I may run a few tests and record my screen to attach as proof.