It used to be a regular thing for me since I already have subtitles on (ESL spouse). The worst is when you have a time shift and a different frame rate, as it'll slowly get worse over time, but seem ok for the first few minutes.
Recently, Plex's "agents" seem to be good enough at figuring it out and auto-downloading subtitles that it's not often a problem.
It used to be a regular thing for me since I already have subtitles on (ESL spouse). The worst is when you have a time shift and a different frame rate, as it'll slowly get worse over time, but seem ok for the first few minutes.
Recently, Plex's "agents" seem to be good enough at figuring it out and auto-downloading subtitles that it's not often a problem.