Both Soundaria and Reactive Music broke backward compatibility.

Make sure you are using the correct version of the mod with the songpack.

• Longer music switch speed except of
  • changing dimention
  • entering/exiting village
  • entering/exiting underground
  • rain or thunderstorm starting/ending
• A lot of new music
  • Raid music
  • Thunderstorm music
  • Pale Garden music
  • Dripstone Caves music
  • Warped Forest music
  • Crimson Forest music
  • Basalt Deltas & Soul Sand Valley music
• Some other small changes