Monitoring must have been deactivated, or the document marked as not relevant.

From the Tests page, navigate to the "..." button on the top right of the page and select "View deactivated tests":

Next, once you have selected the desired test or document, you can click Reactivate monitoring for a test and Re-enable for a document

Next, you may see a pop-up calling out the checklist task if one is associated, allowing you to view the checklist settings before selecting Reactivate

How to deactivate a test

Temporarily deactivate a test