Forms quizzes not accepting teacher mark of zero requiring teacher to review more than once

We are currently using more forms quizzes for assessments and have found a glitch whereby when a teacher inserts a score of 0 for a question this score is not logged when the system autosaves and the teacher has to revisit and mark a second time.  Has anyone else had this issue or does anyone know how we can avoid it?  You can imagine at the moment we are trying to cut down on screen time and this just adds to the frustrations.