I’m running plex 9.12.2.36964 on a Shield tv pro 2019 and whatever I do the subtitle color is white when playing hdr content.
I’ve double checked that the video isn’t transcoding and that it’s a text based subtitle (srt) with no color styling in the subtitle itself. I’ve even checked “override included subtitle styling” for good measure.
Here’s a log from me first playing a file with HDR and then playing a file without HDR.
I’ve also noticed that it’s not just the subtitle color that doesn’t work with HDR. All subtitle styling (position, size, background et.c.) have no effect. All working with SDR.