When one or more quizzes do not show in the LockDown Browser Dashboard, it is typically due to a “null” or an empty value in the submissions view “Message” field. This field permits you to have a message presented to students upon test submission. You can see this field by navigating to the course and quiz, then following this click path:
Edit Quiz->Submissions Views tab->Default View->View Properties->”Message”.
This is a sporadic issue with D2L web services and might occur after a course copy. The quickest way to resolve the problem is to enter some text (even a blank space using the space key) in the “Message” field and save the quiz again.
For more information, visit Respondus’ documentation about this issue: https://support.respondus.com/support/index.php?/Knowledgebase/Article/View/223/0/not-all-my-quizzes-are-showing-up-in-the-lockdown-browser-dashboard.