It looks like external ASS subtitle files have some issue rendering styling tags properly.
Certain styling tags refuse to render properly, certain styling tags are out of sync, etc. I’ve tested it as external sub file on PC players and they render without any issues. It’s only when Plex streams, some style tags break. I’ve only tested using browser and transcoding it through iGPU but seeing as most clients will need to transcode ASS format to display it properly, I guess transcoding is what’s important here anyway.
When I remux the subtitle file within MKV container and attach the fonts to the MKV (instead of attaching it to ASS file itself for external use), Plex seems to render the sub fine.
Is this an issue/bug/limitation of Plex or limitation of ASS, font attachment/loading within ASS file in general?
EDIT: I spoke too soon. Upon testing few more, even after remuxing the subtitle, some tags are out of sync (usually not enough to be an issue for dialogues but issue for blocking where it needs to be frame accurate).
