This is an issue I encountered after I faction changed last October from Horde to Alliance. I just found the solution so I wanted to share for others. I had unlocked all the pet dailies on my Horde character, but when I faction changed I noticed some of the dailies were unavailable for me to do.
Unfortunately they were 3 dailies that offer pet supply bags...
Grand Master Trixxy (Winterspring)
Grand Master Lydia Accoste (Deadwind)
Grand Master Antari (Shadowmoon Valley)
I reached out to a GM who gave me a vague response that I hadn't finished the Alliance pre-requisites for these dailies because I faction changed, but couldn't tell me exactly where I had to go to fix that problem. The trainer in Stormwind offered no quests and it was difficult to see what I had to do.
The solution for me was to go to Eric in Duskwood @ 20.2 44.2 who gave me a non-daily quest "Steven Lisbane". This was where my unfinished alliance quest chain had left off without my knowledge. Taking that quest lead me to Steven Lisbane in Northern STV. Beating Steven lead me to "Bill Buckler" in the Cape of STV in 51.2 73.6.
After finishing that, you're given a quest to go back to Audrey Burnhep in Stormwind. That finishes unlocking the quest-chain to get those 3 daily quests back, requiring you how to finish the quests below.
Battle Pet Tamers: Eastern Kingdoms
Grand Master Lydia Accoste
Battle Pet Tamers: Kalimdor
Grand Master Trixxy
Battle Pet Tamers: Outlands
Grand Master Abtari
Hope this information helps someone else!