DESCRIPTION
It is possible for a student to submit their lone assignment attempt but for the submission to not be marked as the student's latest attempt. In the database, mdl_assign_submission.latest is 0 rather than 1. When this occurs the submission is not counted in the assignment summary and when viewing the page of all submissions as a teacher the student is listed with a status of "no submission". However, if the teacher happens to select the student while in the assignment grading interface the submission will be available to grade.

This situation has been observed on three separate occasions. Unfortunately, I have been unsuccessful in replicating the outcome.

In the absence of knowing how this situation arises, I would propose an extra validation step during the submission process to prevent this outcome.

During final submission of an assignment attempt conduct the following two checks:1. Is there only one mdl_assign_submission record for the user for this assignment?
2. If yes, is the latest column set to 1 for that record?

If the first check passes but the second check fails, update the mdl_assign_submission record setting latest = 1. The logic is that if the attempt being submitted is the student's only attempt on this assignment it should be marked as the latest attempt.

STEPS TO REPLICATE
I have been unable to replicate from scratch. While I have tested with a variety of assignment settings, these are the submission settings in use on the assignments where the issue has been observed.
Require students click submit button: No
Require that students accept the submission statement: No
Attempts reopened: Never

REPLICATION LOCATIONS
Conducted several tests in Moodle 3.3.5 but unable to replicate. Incidents in live courses have occurred in 3.3.3 and 3.3.5.

USER IMPACT
Because the student is not indicated as having a submission on the view all submissions page, a teacher may easily overlook that the students has a submission available for grading.