Dear support team,

Today I had created a new survival world with the Greek Mythology mash-up pack, but to my surprise the vanilla soundtrack was playing instead of the Greek Mythology soundtrack. This had me pretty confused, so I started to do some research to see what the potential issue could be.

Eventually I had figured out that when I created any survival world with one of the mash-up packs, that their soundtracks would never play, only the vanilla Minecraft soundtrack would start playing.

After this I had came to the conclusion that creating any creative world with one of the mash-up packs would play their soundtracks correctly.

This bug essentially makes you unable to start off a legit survival world with one of the mash-up packs enabled. As of now I have not yet found a fix to this very annoying issue.