Anyway, that issue is 1 year old, and subtitles for some reason just keep getting worse with each update. It is not being taken seriously.
It is so easy to reproduce that there must be something more involved to it, explaining why some people dont have the issue.
I tested and validated with these clients: web, roku, android, android-tv, fire and LG
All have the same issue. So maybe some combination of factors with server.
The bugs are different depending on the media, sometimes delayed subtitles and most of times no subtitles at all. Also, trying to switch subtitles to other languages sometimes just dont take effect unless the playback is restarted. Anyway, it is baraly usable.