So I was working on World 6 of Adventures of Jackhack and decided to play the underground music for World 6 in View -> Sounds, and then all of a sudden, THE TOP NAVIGATION BAR STOPPED WORKING! It wasn't just the top navigation bar; it was the ENTIRE ENGINE where the buttons stopped working! I fixed this by closing and reopening the Pocket Platformer tab, but since I hadn't exported my game with the unfinished World 6 before then, I lost all my progress on World 6.

Idk if this is just for Opera GX users tho, don't get me wrong, Pocket Platformer is amazing, just this thing I haven't experienced until today that made me lose my progress

i'm sorry about that and glad you are enjoying pocket platformer. 

I could imagine the issue was that the music has some unsupported format, or something else might have been unstable. I will look into it and for the time being please export your game before playing music files.