So, my friends and I, have been running a server for quite a while, starting in 1.8, and upgrading to stable snapshots. For some reason, none of the playsound commands are working in 15w43c. Each command looks somewhat like this:

/execute @a ~ ~ ~ playsound random.levelup @a ~ ~ ~ 10 2 1

It says that the command has been successfully executed, but my friends, and I can hear nothing. Every game sound that is not through a command, however is fine and can be heard as normal.