In a filter or in an advanced search, a search on a Time type field with the "IS EMPTY" and "NOT EMPTY" compound operators do not output the expected results.

For example, assuming that DateOfUpdate is a Time field, the following search criteria

The expected result here is only entries with empty DateOfUpdates to be displayed.
However the search retrieves entries where the DateOfUpdate is both empty and non-empty.

The expected result here is only entries with non-empty DateOfUpdates to be displayed.
However the search retrieves entries where the DateOfUpdate is both empty and non-empty.

Reference: https://moodle.org/mod/forum/discuss.php?d=316873