
This is likely due to the "Reportable" field being checked at the project level (whether intentionally or accidentally). In order to prevent double entry of time tracking hours, checking this at the project level will uncheck that field from all tasks and milestones in the project. So in this case the tasks will disappear from the timesheet and the project will appear instead. If you want the tasks to be reportable, you should make sure that "Reportable" is unchecked at the project level and the field "Allow Reporting on Sub Items" is checked.