I was going to skill break Gaara. I had 100 fragments saved up. I bought a skill book for 50 fragments for "Defender of the Land of Wind", for the first upgrade. I did this ONLY once. It bought 2 books and spent all of my fragments, so I could no longer get the skill book for Sand burials first upgrade. This is incredibly frustrating as I have been saving up Gaara fragments for months to be able to start buying skillbooks for him. The bug occured August 23, 2018.