Here's my discord: h8rsk8r#0974. I've modified the "gml_Script_jukebox_advance" script as was explained in the guide, so it might be a problem outside that, or maybe I made I mistake somewhere.
For those who are interested in H8rsk8r problem solution:
They recreated all the process of modding the game from zero and the problem was solved.
Looks like some code was copied or pasted wrong.
