Why is "Unassigned" the only option available from the TFS 2013 agile task board? Why don't I see a list of team members. I have assigned team members to the team project. Also, if I open the task to get at all of the details, the Assigned To field has a list of all the users I would expect to be able to select from the agile board view.
Here's a screenshot of the Agile board where I am trying to assign the task to someone, but only see "Unassigned." I also cannot type in the field.
In my experience, this was related to capacity. For each sprint, you can set the number of hours per day and days off per user. I found that if a user was given 0 hours capacity for the sprint, they would not appear in the drop-down on the task board.
I think you don't have right in order to access your members, i suggest you to access security section in your Web Portal, check your Group and permissions associated.
try with administator group which have all permissions
This is late to the party, but in my experience this is because the drop down from the task board item view only includes team members which already have assigned tasks on the board (unless you set capacity, as above). If you edit the task by double clicking on it you can assign whoever, and then that person will appear on the drop downs for all other tasks on the board.