8.0.2b posted in OP. Changelog in short: performance improvements.
Thanks for the new release and awesome work again. Unfortunately, the sound issue is still there.
At least, I could find out, what the files have in common:
Audio: AAC 22050Hz mono 59kbps [A: English [eng] (aac lc, 22050 Hz, mono, 59 kb/s)]
It seems, Libreelec (or Kodi) has problems with AAC 22050 Hz files, because the sound gets distorted/broken.
Is there a way we can fix it in the settings somehow or has it to be done on your (developing) end?