[GeoffR]

If the book had been read and marked as finished, then opening it at the beginning (which shows as 1% progress) is the proper behaviour. (And I hope that doesn't change, it would be a right pain if it opened at the end.)

If the book has been read and not yet marked as finished, then it should open at its current position. If it forgets its current position and opens at the beginning instead then that could indicate a corrupt database. (Edit: or a faulty book.)