This achievement is the one you get for tossing the ball back and forth with your hatchling in the Arboretum. I reached 15/25 tosses, when my dragon tossed the ball into the pavillion, and it got stuck underneath the ground. I can't pick it up, I can't toss the ball again (you can't do that yet), and when I talk to the npc to tell her I'm done and try to start it again, it still continues to tell me I am unable to do that. The counter on the achievement is also stuck at 15/25. Opened a ticket with a gm, but figured it would get more notice here.