Too bad we cant start off-topic threads. Because this is one. A few weeks ago some upgrade broke closed captions in my computer. The only application which can properly display closed captions from live digital TV stream (TVHeadEnd) is Kodi. All other apps show some gobbledygook, mpv, Handbrake, etc.
Question: what library is used to extract CC from MPEG-2 TS? I need to start troubleshooting somehow.
I'd guess that it's all related to ffmpeg somehow - you may find that Kodi and tvheadend are both built with a static library, so aren't impacted by a system-level upgrade, but other applications load in the relevant .so or .dll (platform-dependent) as required.
That's where I'd start. If you're using tvh, you're probably on Linux, so have a look in /var/log/apt - you'll find history files there, some compressed. Grep around a bit and see what was upgraded around the time things broke.
You could also try moving/playing a recording on a different platform that hasn't been upgraded, that'd help establish where the problem physically resides (i.e. on which client, on all clients, on particular applications, whatever).