I have enabled subtitles in the Apple TV settings and chose the "Transparent Background" style, but when I go to play a mkv file with embedded subs/sub style in the container, it uses the fonts/color/background from the mkv file instead of the Apple TV setting. Can't seem to find any settings in the Channels app related to subs that might help this issue. I have tried a custom style, and disabling allow video to ignore style for each option, but it did not have any effect. I am on the latest Beta version for Apple TV.
Channels will only use the standard Cc Style captions
Not for me, it might default to that, but it's definitely using the style from the srt or embedded subs.