Server Version#: 1.31.2.6810
Player Version#: 9.19.0.177
Not sure how long this has [potentially] been an issue, but I just noticed this recently.
I went on vacation and used the Android app’s Offline feature to watch a movie so I downloaded it ahead of time but I didn’t have subtitles for it. While I still had internet, I went into Offline to see if they could be added, but there’s no option.
I used the Search… option (as opposed to local SRT like I normally do) to find subtitles when I arrived and redownloaded at my destination for the return trip, however when I tested the file it still said there were no subtitles, even when they had been added ahead of time.