Sometimes you might sync an employee's shift from the timeclock or portal yet their pending pay is still unaffected, or remains at $0.00. This is most likely to the shift itself not having any pay items (pay rates or allowances) connected to it. Please check under Employees >> Shifts to make sure the shift total is not showing as zero dollars.
Another reason the shift might not be available for syncing is if it has been deleted from the employee's shifts. Once a shift has been deleted or disconnected from an employee, it can no longer be synced.