I can currently only confirm this for tv4play for all video formats
DL is fine (example: Sullivan’s Crossing.s04e01)
"remuxDownloadedFiles subtitle stream, langCode :swe, path : ../Period_00/Sub_00/st_00, bForced :0, size :82385"
but simply no subtitle in ffmpeg command line:
StartRemuxMultiAudioSrtMetaUtil pid 13768 cmd: \".. ffmpeg.exe\" -hide_banner -y -i \"../Video_00/vt_00\" -i \"../Audio_00/at_00\" -map 0 -c:v:0 copy -c:a copy -dn -map 1 -c:a copy -metadata:s:a:0 language=eng -metadata:s:a:0 title=\"\" -metadata artist=\"\" -metadata date=\"\" -metadata description=\"\" -metadata title=\"Sullivan's Crossing - Avsnitt 1, Säsong 4\" -metadata show=\"\" -metadata comment=\"\" \"../outputTemp/DRM M3U8/../2026_07_24_02_15_35_remuxVideo.mkv\"\n"
btw: Same result with mp4 and mkv(mkvtoolnix)