Normally when you enter an area that has specific music playing (or hit a radio in some cases) it adds the song to your list. This is a requirement for 100%. Today I found a track (#20, 8-Bit Lost Isle) missing, even though I had been to the only place in the game which uses it (2D over the fuzzies wall). I am not sure whether this is a glitch because of avoiding the Keepo Vulture (its cutscene changes the music) or what, but it caught me by surprise. Has anybody else noticed music not being added to the collectible list?