Tim Hunt

What you want (in a single question with mulitple sub-parts) to do is possible with the STACK question type https://moodle.org/plugins/qtype_stack - but that is not the easiest plugin to install because in addition to the Moodle plugin, you also need to install the maths processing software (Maxima) which it uses.

The other way to achieve what you want with standard question types is to create each separate variant you want as a separate question in the question bank (since they are multip-part qusetions, they would need to be Cloze), and then use the Moodle feature to add one picked at random to the quiz: https://docs.moodle.org/310/en/Effective_quiz_practices#Robust_testing_with_random_variants. (The down-side of this method is that you have to create and maintain multiple questions.)

It is a fundamental part of the design on the Moodle quiz that each question is independent.

Some questoin types (e.g. Forumuas, STACK) support a single question with multiple sub-parts, which can then depend on each other. That is the only way to achieve what you want. (I would not recomment hacking this with JavaScript.)

If you are going down the Docker route, I would recommend running Maxima in a separate container. These nice people have done most of the necessary work: https://github.com/mathinstitut/goemaxima.

In each quiz, go to Setting -> Check permissions, and cehck the permissions for a student who has attempted the quiz. See if there are any differences.

It is more likely to be a server log file. goemaxima runs in Docker. I would look at that log, and any other system logs which seem relelvant.