This was an intentional change.
With the new Family Battler achievement, we changed all of the Kul Tiras and Zandalar trainers to allow them to be battled at any time. This makes it so that players can complete the achievement at their leisure, rather than having to wait for a specific World Quest to become available.
At the same time, we increased the chance for pet leveling stones to be a World Quest reward, and reduced the chance of both battle pet bandages and War Resources to show up as potential rewards from pet battle World Quests.
See original post here.