Quizmaker crashing when student attempts to answer question

Around 5-10% of the courses we have sold this year have failed because a Quizmaker Quiz in the course crashes when a student answers a question.

As the answer is selected, a red bar with Incorrect on it appears at the bottom of the screen. The red bar is what is shown for a wrong answer in a Review of a Quiz.  The only escape is to Exit the course. Here's a screenshot.  We reported this many weeks ago, but the only fix suggested was to ensure that Transitions in the Quizzes should be set to None. We did that, but the failures continued.  We deal with it on each occasion by running the course in the student's LMS account until we reach the test, then taking and passing it, then logging out so that when the student resumes it is on the slide following the test. This is not satisfactory in a regulated industry such as aviation.

We have changed each course so that there is only one test (Quiz) at the end. We are testing these in SCORM Cloud before uploading into the LMS. An hour ago we experienced this failure on the first question of a Quizmaker test in SCORM Cloud. 

This problem is beginning to destroy our business. Our market is a small community of expert professionals and word spreads quickly.  I sent an email 2 days ago to Articulate Support stating that and asking for urgent action to investigate the problem and come up with a fix. It is intensely disappointing not to have received any response. It is intensely annoying that each follow-up email, which has the Case No in the Subject line, simply gets an auto-response with a new case number.

I'm attaching the ZIP Presenter output for the course that failed in SCORM Cloud just now. If you need a Package please let me know.