I've read about it on PUP forum, but i thought it was only for bcnm/htmb fights so i wasnt that worried about it.
But it actually happens also on mission fights on non-instanced areas.
I just finished fighting the mobs for TVR 5-6 "The Seagull Phratrie" where you have to "click" the glowing thing on the ground to pop the monsters, and my pet despawned.
Does that mean that it will happen also on unm, vw and vnm fights??
If that's the case, it definitely needs to be fixed.