This is very strange, the assignment shows only one participants, then any additional submission after that from other students doesn't appear in the participants list ( see the image below)
Users are keeping submitting, but submissions are counted in the submitted count and those needs grading, but you can't view or grade them
Yet they are still available for download.
This is only happening in one course in my moodle 2.9.
Any assignment created under this course will behave the same, while any assignment under any other course work perfectly ??
I will be grateful if anyone has a clue
This gave me a bit of a clue.
Although there is no group set to it,
However, I have 2 roles, students A and students B
I have notice that I can see only those students who have the role 'Students A"
Any student I assign role "Student A" will appear and vise versa.
Do you have a clue?
I have checked that, and it is OK, this is happening only on a single course level !
Looking at this again, I think it is that you do not have access somehow to this specific group of students in this course. Obviously the students are able to submit so they have the correct access. It is more that you do not have access to see the submissions.
By chance, are you in the same group as Student A and not Student B students?
When you click on View All Submissions - is there a group dropdown list at the top? Is there an option to View All Submissions from the grading screen?