This may be confusing... but the item totals only show labor hours if you estimate the labor costs using the "Rage and Productivity" tab.
To see what I mean, follow these steps:
Select an item that has a labor cost.
Click on the labor cost for that item (the icon with the hand holding the wrench). This will take you to the labor cost entry screen.
Click on the "Cost Per Unit" tab at the top and enter the labor cost in terms of cost per unit.
When you go back to the item total view, there will be no labor hours shown.
Click on the labor cost again (the icon with the hand holding the wrench) to go back into the labor cost entry screen.
Click on the "Rate and Productivity" tab at the top and enter the labor cost in terms of rate and productivity.
Now when you go back to the item total view, labor hours will appear.
The reason for this is that the program can only know the hours when you use the "Rate and Productivity" method to calculate labor cost. When you use "Cost Per Unit", the program doesn't know that the unit is in hours, even if the unit you assigned is named "Hours". That may not make sense, but to explain, what if you named the unit "Hrs.", or misspelled it as "Huors", or if you live in France and called it "Heures". The program is not able to assume that any particular unit you define is equivalent to hours.
So, if you want the item total to show hours, then you must always use the "Rate and Productivity" tab to enter estimated labor costs.