Affects Version/s: 3.1.3
Fix Version/s: None
Just pointing out a small in feedback activities, Students are not able to submit their responses if there is a multiple choice rated question left unanswered (the question is marked as non-compulsory) and not selected option is hidden.
By debugging the code i noticed for above case non-compulsory multiple choice does not save in mdl_feedback_valuetmp table.
And function get_last_completed_page() mark this item as incomplete and form never will submit.
i have small patch for this in the get_last_completed_page() to check if item is not required then mark as complete.
classes\completion.php line 270
I will add the patch to github for your review.