Incprrect, ignore

In the default resources' "sounds.json", there are four triggers for wither skeletons: mob.witherskeleton.hurt, mob.witherskeleton.death, mob.witherskeleton.step, and mob.witherskeleton.say. In my resource pack, I added custom sounds and changed mob.witherskeleton.say to mob.witherskeleton.idle in both "sounds.json" and "sound_definitions.json". The images included show the JSON. In-game, however, the wither skeletons still use skeleton sounds, instead of the custom ones specifically for them.

All the sounds work when they're played with commands. The wither skeletons themselves are the issue.

Nevermind.