Yeah this seems like a skill issue, you need to make sure your food is high enough level, cooked food normally is always better then raw and after like rank 2 or 3 pet loyalty the pet doesn't even need to be fed that much unless he's constantly dying.
Both the mobs in the Kuzan Cave in north STV and the Waterwanders mobs in Tanaris do not lose stealth when aggroed, they continue to attack but do not lose their stealth status.
There is multiple areas in Balor where the hunter pets just dont want to path towards the mobs, they are stuck in place when you send the attack command but they will follow the player fine.