I just ran into this strange behavior after upgrading Microsoft Project server from 2007 to 2013.
After the upgrade a team member was able to log time against a task, it was sent to his manager for approval, his manager approved his time, but time was never visible in project. So, ‘Actual work’ remained zero hours after all this.
Cause and Solution
Initially we thought the behavior would have come over from your PS 2007 and it was working as per PS 2007 PWA settings. But that wasn’t the case.
There is a setting shown below in PWA where “Task Status Manager Approval” is set to be “Disabled”. This means that you can’t go to ‘Timesheet’ section and update task hours. You have to go to “Tasks”, update hours, get it approved and publish the project plan to see the hours reflected for tasks.
Hope it helps! If you have any questions please contact us.