Can't play mp3 audio files in-game

Trying to play any mp3 file from the Gmod, either by using play command in the console or any sound tool in-game, gives:

Create Stream Failed error 44
Failed to load sound "filenamehere.mp3", file probably missing from disk/repository

Gmod version:
13.10.24 (dev)

I don’t know what this error 44 means. Sadly I had no luck in finding any info about it online. Any ideas on what might be causing it?

What was tried already:

  1. Verifying the gmod game cache.
  2. Verifying the half life 2 game cache.
  3. Trying to play a mp3 file that is in the directory …/Garrysmod/Garrysmod/sound/