The issue is that the assets load asynchronously, and I didn't have the time to implement it waiting on all the assets to load before letting you out of the main menu.....
Which is particularly bad with the music because that one starts at 1. The moment it is started in code 2. The moment it's loaded, whichever of the two comes later (it needs both), so if you start before the music is loaded, it starts the music too late causing everything to be out of sync