I know basic questions…:-) Unfortunately for helping debug your scenario, I’m a 2013 user. So here’s questions we ask when we see timesheet issues.
Was the timesheet Saved, Turned In? Was the timesheet hours approved by both levels of approvers. There’s an approval level at the timesheet which pretty much says the hours are approved (for example, yes, the resource was here for 40 hours). There’s also an approval at the project status update level where the PM approves the individual task updates. If you look at the Status Manager for the problem task and go into their approval queue in PWA, can you see where the timesheets where processed with no issues? Are the actual hours submitted with the original timesheet in the schedule and in the correct time scale data periods, but just not showing up in the timesheets? For example, maybe the task is now completed and when the timesheet is re-opened, the task doesn’t appear anymore because the task is now completed. Could the timesheet processing be held up in the processing queue for some reason? Sorry I can’t zero in on any one solution. Hope these help.