Playsound for custom sounds does not work when selected in game, until the game is closed and restarted completely

What I expected to happen was...:
Work without restarting having to Minecraft.

What actually happened was...:
Did not work until Minecraft was restarted.

Steps to Reproducing
1. Load a resource pack with a sound.
2. Go into a game, and type "/playsound (name of sound) @p
3. It does not work until after you restart minecraft.

NOTE THIS DOES NOT HAPPEN WITH TEXTURE PACKS