I added custom music to the more music resource pack and enabled it, but when I try setting it to play in specific biomes in game using the configurator, clicking "save" causes all my progress to be undone. Any clue what causes this?

Hello, thanks for the report! What Minecraft and Music Control versions are you playing with?

Oh it seems that indeed when you click save, after the reload, the screen is still open and doesn't contain the changes. However, it is saved and closing/reopening the menu shows your changes. Can you confirm?

nope. no save on my part.

Alright, so what Minecraft and Music Control versions are you playing with? Don't hesitate to go on my Discord for easier exchanges

Reading again your message, I noticed something. You said you added music to the "More Music" resource pack and then you don't get the changes when saving. The "More Music" resource pack is just an example resource pack to add new music to the game. It doesn't handle the custom event saving system. This is done in the auto generated resource pack of the mod, that needs to be enabled (named music_control). On the latest versions, the music menu forces you to enable one before configuring, but before the 1.7 release, you had to it manually (this might be your case).

Without update on the issue, I will need to close the issue. Please let me know if I helped you