Good But a BUG in Book Mode! – Big Bad Sudoku Book Review

When playing in Book Mode, say puzzle 20, and I exit the app and return. It saves my place in the puzzle but upon completion it DOES NOT unlock puzzle 21. It makes me replay 20 start to finish without exiting the app. Five times now. VERY irritating. Something I'd like - double click a number and have it highlight every location of that number in the game. (Fix the bug first, please!)
Review by Maiasatara on Big Bad Sudoku Book.