so the bug is this, if you put tnt on lava its took time but when the lava balls reach the tnt its getting flame and when its explodes it's destroys... You will not belive but it's destroys NOTHING!!!!!
I think it's related for an older bug you fixed, the bug that squids could spawn in lava.
Works as intended - Water and lava block explosion damage, unless you count waterlogged blocks cause they are affected by a bug