I have just upgraded my iOS to version 9 on iPad Air and now Brush is unusable. I can open it but if I try to edit an existing brush or create a new one the app crashes on me. Any ideas on how to fix this would be appreciated.
Try turning off bluetooth on your iPad. There's an iOS9 driver bug in our stylus support and we're working on a fix. In the meantime, turning off bluetooth on the device will disable the stylus support, and avoid the crash.