When using the "playsound" command with longer pieces (in this case, a 4 minute sound file I've added via resource pack is used for background music in an adventure map), the sound will not always play to completion; sometimes it will only play for ~30 seconds, other times the game will make it several minutes into the piece before stopping.

I've read that this is being caused by other sounds playing (the execution of other "playsound" commands or other natural sounds (mob noises, block breaks/placements/interactions, etc), but after a little experimentation I couldn't replicate any reliable scenario that would cause it to cut off.

My command:
/playsound bumblebee master @a ~ ~ ~ 200.0 1.0

This issue has two other submissions (that I could find), but both are closed as incomplete:
MC-18789
MC-26927