taking no damage

I am out trying to find the rare clothing merchant, and had 3 red wyverns attack my water pet, and there was simply no damage for around a min, however, as I was getting to this page to report the issue, the pet did die, and all three were attacking me, now it was me that was taking zero damage, but eventually dmg does begin, its like my pet and I have some 10k hp shield around us.

 

In the encounter after, I did a dog encounter, all dmg received correctly, however, the next one was another barbarian encounter, and my pet took zero dmg for about 2 min with 2 red and 1 purple wyvern attacking.

 

Could you use the /bug command in game and post that information here next time you encounter this.