dunno, everything works on my side...
do you see an audio stream icon with "1/1" (1st stream of 1 total streams) in the mpv's controls (next to remaining time counter)?
reinstalled svptube and set it to use the default bundled mpv player and now it works, previously tried it on custom mpv like smplayer & mpv.net. It still doesn't work on vlc though I tried reinstalling that but still nothing.