Mesmerize

When mobs are mesmerized, why do they become unattackable and their health regains as if they are out of combat. Is this intentional or being worked on? If there is a dot on mob it still damages but seems like other direct attack don't even hurt the mob maybe because health regeneration goes up like they are out of combat?

 

.. was with guildies today.. and i can most definitly break mes on mobs?
Auto attacks.. skills..
Nothing changes?
Bug maybe?

 

Mesmerize seema to be working exactly like the Charm Animal spell. When I use it, it puts the mob out of combat then they start regenerating faster.

 

I can attack them but it doesnt hurt them unless its a DOT i rechecked last night. also i dont think NPCs should regen health so quickly when mesmerized, if they have to regen great, but at a much slower rate. Lets say im fighting 3-4 mobs and have them down and mesmerize them for a sec to heal or run a bit whatever. They shouldnt regen back to 100% in like 2 seconds.