Storyline 360, two quizzes, one course, can't reset quiz

Hi, I have a course that's made up of three scenes: 

• The first scene doesn't have a quiz.
• The second scene has a Knowledge Check (i.e. no marks to LMS) that pulls 10 questions randomly from a pool.
• The third scene has a Post Test (i.e. marks are reported to LMS).

This has been a nightmare to get working, because the Results pages from the second and third scenes would only use the built-in Results variables and kept overwriting each other.  I fixed that by creating a custom variable for the second scene called KnowledgeCheck_score and adding one to that variable every time the student got to a Success layer on a question.  That allowed me to get to the Success layer on the Knowledge Check. 

Unfortunately, if the student fails the Knowledge Check, there doesn't seem to be any way for me to unlock the questions for them to try again.  I have marked all the questions first as "Return to Initial State" and then as "Automatically Decide" - neither worked.  I can't add a Reset.Results trigger, because it only gives me an option to reset the post test from the third scene.

Can anyone help?