I was able to resolve this issue, here are my notes:
- Windows was having the same issue, leading me to hardware/BIOS settings
- Hardware encoding was working, out of the of the box on 18.04 w/HWE and 18.10, you don’t need to adjust the kernel. This was mostly a vocabulary thing on my part once I understood that PMS asks the API for each path what to do independently (decode vs encode)
Then I found this thread: Plex hardware HEVC decoding not working with Quicksync (Multiple Graphics Adapters)
and ultimately my solutions here: What's the status of Hardware Acceleration on headless Windows machines with RDP?
I realized that the display attached to the system was my TV, but when I was doing testing I was flipping that same RokuTV to another source in which case the HDMI signal to the server would drop. When the test would run, I’d get encode only, that is until I used a different client to test and left the TV set to the server’s HDMI source and voila… hardware encoding and decoding.
tl;dr: If you’re going to run Windows headless using onboard Intel UHD graphics, go get an HDMI dummy cable so the display think it’s initialized all the time. If you’re going to run Linux headless on the same hardware, you may see the same issues, I’m not reverting back to Linux at this point. I’d imagine that using a dedicated GPU could change this behavior considerably.
