Students can only see their own results (marks/grades/comments).
If all the marks, grades, comments and statistics are set to No, the yellow flag will appear. Students will not be able to see the graded item (and the results) until you are ready to publish.
On a Gradebook (List View):
To publish the results, select the graded item and click on Edit Publish Settings button.
On a List View:
On the modal, select the information to publish to the students. Then, click on Save button.
If you do not want your students to even see the graded item, you need to remove the access under the Permission tab. (Default is Everyone in this module.)
If you have published your the results to the students, you may Send verification reminder to the students.