Still in 1.11.2 - Snow golems will attack creepers, and in return, creepers will target the snow golems.
Also happens on v1.11.2.
Happens to me too. Can really be used as an exploit, because if I keep doors open, zombies cant break them and wont go through them either.
EDIT: Looks like not all mobs are affected. For example, adult zombies are, but not baby zombies.
Cannot reproduce anymore.
Happens in my worlds too. Turning music to 0% wont stop it and if I let it at 1-100% it will sometimes play 2 tracks at a time.
EDIT: Sometimes launches w/ no music. Thanks for the F3 + T tip though!
Updated to note it still happens on 0.15.10
Happens to me too (1.11.2)