Piglins and Hoglins aren't able to make noises. I have not heard a single noise from either, both in this snapshot and the previous ones.
EDIT: I have managed to get the sounds to work by redownloading the snapshot, but I don't understand why they didn't work beforehand. That is the issue.
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Check your sound settings, what's the hostile mob sound slider set to?

@Greymagic27 All sound settings apart from Music are set to their max. At first I thought the issue was due to use of resource packs, however when I disabled the few resource packs that I use and relaunched the game, the issue persisted.

Duplicate of MC-165967. The issue is caused by the version .json
file not being updated correctly, causing some textures, models and sounds to become missing.
Can't reproduce