Moodle 3.5+ (Build: 20180607). php 7.1.22. Database: mariadb (5.5.5-10.2.17-MariaDB). All Environment > Server Checks are shown as OK. Hosted on a managed dedicated server with Rochen. Cron is verified to be running as expected. Caches have been cleared. DB has been repaired and optimized. Users have cleared local browser cache and issue persists. Site runs under https.
Course was built under Moodle 3.3 I think. Possible 3.4 or 3.2. It was upgraded to 3.5+ a few months ago.
The Problem: in Quiz assignments, some users are seeing questions from other Quizzes. I cannot verify that it is tied to any specific user or role/permission set. Sometimes it seems like it might be a cache issue, but I can't verify that.
Example: a user goes to a Quiz in week 1 and it work as expected. Next week, they go to a Quiz in week 2 and see the questions from week 1's quiz. When I log in as them, though, I see the correct questions. We have rebuilt a quiz and the issue persists.
Any ideas as to why the wrong questions would be showing up in Quizzes? Have I misconfigured the Quizzes or is the Question Bank somehow shuffling questions around the course unbidden?