After submitting a timesheet, the team member can not 'return' the time sheet - there is no selection to do this. This functionality was available before we added the project manager approval process for timesheets (timesheets are approved by the Project manager & the Resource manager.)
Select the check box next to a submitted timesheet & select the button - return timesheet. You get an error message TMA-0122: One or more timesheets' status could not be changed because it is locked by a process.
This is functioning as designed.
Once a Timesheet Process is initiated, by the nature of the Timesheet Approval Process, the timesheet status is locked and only the designated Timesheet Approvers can return the timesheet.
End users may have a short window (before the timesheet process kicks off) when they have the ability to return the timesheet themselves, but once the process has been initiated, the timesheet status is locked by the process.
Reference TEC438723 : Timesheet locked by a Process that may be stuck resulting in an error TMA-0118 or TMA-0122
Reference TEC439635 : Approving Timesheets after an approval process is initiated
Reference TEC444563 : How can I limit the project manager approval process to select groups?