FriendlyFire-1.12.2-1.5.9
BabyMobs-1.12-1.5.5
Forge 14.23.5.2807

The BabyMobs version of the Cat that follows around the Minecraft Witch [not the Ender Zoo Cat] has the label "tamed" and you cannot attack it [not sure if the label matters but so far the only mob I have found that has a issue]. One of my players thought it was a joke until it got serious; He died.

Will be sharing this with FriendlyFire as well.

Thanks will try and report back

My guess is you have protectBabies enabled in the FriendlyFire config. Disable that or sneak while attacking the baby ocelot.

That was it. Thanks again.