If you summon an invulnerable passive mob and set it on fire, it will run around as if it were taking damage even though it isn't.
Linked issues
is duplicated by 1
Comments 2
This has apparently been fixed in 1.10-pre2 (MC-102408).
MC-78688
Invulnerable mobs still act like they are taking damage in fire
Resolved
Fixed
1
Unconfirmed
Minecraft 1.8.3, Minecraft 1.9
Minecraft 1.10 Pre-Release 2
Retrieved
Is this still an issue in the current Minecraft Snapshot 15w49b or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.