The bug

When an armadillo rolls up, no sound plays despite there being a sound in the game for it (mob.armadillo.roll).

Steps to reproduce

1. Create a world with the 'Armadillo and Wolf Armor' experimental toggle turned on
2. Run '/summon armadillo'
3. Sprint near the armadillo so that it rolls into a ball
4. Listen to the armadillo and note there is no sound

You may hear a different armadillo sound when it rolls up (namely the landing sound) - note that this is a different sound.

There is a sound in the game for an armadillo rolling up which can be accessed using this command:

/playsound mob.armadillo.roll