I think Storm Peaks is one of those zones that's either completely full of pet or not at all at any given time. The first time I went there, it was completely devoid of any critter. Second time I passed over the Maker's Engine and there were wild pets galore. (I've completed nearly all of the zone, just for reference.)
I don't doubt that phasing is an issue for the area, but at the same time I think luck is a large factor. That and the zone population, since pets seem to spawn more and more often with more players in a zone. (Based on observation so I could be wrong; I haven't heard any official confirmation on this.)
Direbane wrote:If you're quick enough there is a method of engaging these pets before they phase out.
Bind a key to the function "Interact With Target" in the keybinding interface. Make sure you chose a key that you can easily and quickly access while still maneuvering your character. Position yourself in a way that makes it so yo can click on the pet to target it, but not close enough that is phases out. Once you have it targeted quickly swoop down on it and spam that key you bound. If done quickly enough you can initiate the pet battle before the little bugger has time to get away!
I've used this trick countless times with great success, particularly when trying to catch those sneaky Twilight Fiendlings in the Twilight Highlands.
I've had phasing issues too, with or without having completed the quests in a zone. It's so odd and frustrating because I can't tell if sometimes I need to be further along in the chain or not have done it at all.
Another
trick for nelf druids or any class that has an attack that doesn't do damage but causes agro, and an agro dumping ability: Cast Faerie Fire onto the pet, wait until it gets close enough, shadowmeld, wait for the cursor icon to turn back into a paw print, and then engage in battle. This works for pets out of range, in spots that are too uneven to battle, and phased pets.