When I had a pomeranian, she used to only lick the peanut butter and then walk away.
My yorkie is very picky. She likes to chase her Kong when there are treats in there (that she doesn't like), but she can never get them out and loses interest quickly.She doesn't like it when it's empty either.
Also, when the Kong bounces and rolls on the floor, it scares her!!
I guess every dog has their own likes/dislikes... maybe yours just doesn't like the "world's best dog toy".
It's like, when you buy an expensive toy for your baby, they play with the box it came with instead. 