Another situation is the LG WebOS TV. ASS is supported (although I think formatting is stripped), but Plex doesn’t offer the option to passthrough the ASS subtitles because it thinks they aren’t supported, I’d suggest the option of “Prefer subtitle downgrades before transcoding” (ie stripped formatting).
Link to topic I made with more details: Plex App forces CPU intensive transcode for subtitles while DLNA does not
