Imported Brushes Disappear in Fresco

I imported a number of brush libraries into Fresco and they have disappeard. I had spent hours going through them and marking favorites. I am on an iPad and had saved them in my files in a folder called brushes. After their disappearance, I have tried importing a set, and they are still there after restarting my tablet. What is going on? I don't want them to disappear again and I lost hours to this.