Branching & Random questions

Hi everybody!

I've created a very big branched learning object: it's an hour long video divided into 12 parts of 5 minutes each.
The customer requires moments of test in order to verify that the user is actually in front of the screen. That's why he wants the tests to appear randomly in different moments, so that the user cannot forecast them.

In order to create this specific effect in Storyline, I worked on a complex structure of different scenes linked to each other as representend in the attached image. You can see only the first part, but you'll understand.

If the user provides the wrong answer, he/she has to repeat the related section. The question banks randomize 5 questions in order to present just 1 question at a time.

It all works, but there's a problem I can't work out: as you can see in the image, if the user gives the wrong answer in the first scene, he'll jump to the beginning of the second scene, go through 4 modules, then get to another question bank. If he misses the answer again, he'll go back to the first scene.
That's how I managed to create (almost) unpredictable test moments.

Here's the problem: once the user comes back to a previously visited question bank (no matter which one), it does not randomize the question, so it always appears the first randomized one.

No good... no good at all...

Why?