This is on allthemods from v1.38b to v1.39 now

the crystals are not able to be damaged anymore, even block breakers and pistons do nothing.
also if i summon the dragon the vanilla way and kill him even w/ the health regen, no dragon heart drops.
the animations of the dragon being healed have also stuck at the top of x0, z0, even though he's dead

That sounds more like another mods issue. I dont in any way modify the vanilla dragon than forcing it to spawn an egg every time it dies and dropping the heart. Nothing i do could cause what you are describing.

@brandon3055 any suggestion/idea on which mod it might be? have you run into issues in the past of other mods messing with this?

Have you or anyone edited the End or tried to reset The End at all ?

I have, and we also upgraded allthemods to 1.40 and ran it w/out sponge, worked fine.

Put sponge back, end crystals wouldnt blow up again, dragon wont drop hearts. I think it might be sponge

Then id say its a sponge issue an not DE ... The End also requires more then jsut del the world folder of it to reset, but it seems clear that the issue isnt in DE but sponge.

@Morpheus1101 agreed