I have a world that does have custom music / sounds for various things. One track that is 3+ minutes long that is a custom sound seems to break various other sound effects from playing sound. For example, when I hit a player they do not create a hit sound and random.orb does not play when I get XP or even at times when I just run the /playsound command.
Vanilla tracks do not seem to break it but I have not tested this very well, only with pigstep specifically. I should not we used .ogg files for the custom music.
IMPORTANT: After hours of testing, I think this may be related to playing too many sounds or tracks at once. The custom and vanilla tracks that were only 50 seconds long that worked fine before seemed to break after multiple sounds from various entities were playing. Specifically, the one we are worried about is the sound played when hitting a player (the hurt sound). However, the random.orb and a few other sounds seem to break randomly from similar circumstances.
It seems vanilla sounds are what breaks as a result, I have not had an issue with resource pack added sounds.
To Replicate:
Play a custom track (the one we played was 3min long)
Hit a player (the sound will bug)
I attached three videos of three different scenarios:
this is probably intestinal to stop a lag b an unnecessary ear drum burst