Hi Lynda,
The default functionality of Workfront is to change the status of a request (or issue) to resolved when the done button is clicked. However you are able to customise what status is applied when done is clicked for different teams. The article here on Workfront One explains in more detail.
If this is not what is causing your issue, there are a few other things I would look at . . . .
(1) If the request is assigned to multiple users and one user has clicked 'done with my part' as opposed to resolved (or whatever status is used in your environment), then the request will dissapear from that users worklist but the request will not be set to resolve because it is still waiting for other assignees to mark their part as done too.
(2) If you are converting your requests to tasks (and a task is what is appearing in the work list, not the request itself). It could be that Workfront is not configured to tie request resolution to it's resolvable object. If you are an admin, go to Setup>Project Preferences>Tasks & issues, and in that section there is a setting for 'Automatically update Resolvable Issue status when the status of the Resolving Object changes'. If this is deselected, request (issue) statuses will not get updated when it's resolving task is changed.
Hope this helps!
Best Regards,
Rich.