I can provide the exact command or steps for your specific situation. [Now released] Restore MKV Format Support - Adobe Community
Use --embed-subs and --sub-langs "all" to pack all available subtitle tracks directly into the file. Download stream (3) mkv
If you need to play the file on a TV or use it in Adobe Premiere Pro , you may need to "Remux" it to MP4 using OBS. I can provide the exact command or steps