Disappearing notes


I can write pages of notes, go to another app, then return to NotesPlus to find they have all disappeared. I go to another app again, return to NotesPlus and maybe they have come back again. I annotate notes made earlier then next time find my annotations have disappeared. In other words the app has become totally unreliable. This started happening after the last update. I use an iPad Pro with the the latest iOS and an Apple Pencil first generation. Can anyone help?