Seeing the same thing for PGS vs SRT. I can burn SRT in 4k content just fine, but not PGS.
Here’s a good thread explaining what’s going on: Plex 4k transcoding "not powerful enough" only on some files
Basically comes down to plex not being able to utilize ffmpeg the same way you or I could via the CLI due to licensing. Hopefully Plex can negotiate better terms.
