Slimes and Magma Cubes don't play sounds when attacking in Bedrock, even though these sounds are in the game. You can see this by running the command /playsound mob.slime.attack

Step to Reproduce:

1. Spawn a Slime or a Magma Cube
2. Go into survival
3. Get attacked by the Slime/Magma Cube

Expected Result:
The attack sound plays

Observed Result:
The attack sound doesn't play