Hello d/c,
Replace the =SUM() formular you have by following the steps under the Autosum button on my earlier answer. For SmartSheets that expand and collapse, you cannot use =SUM() in any area that contains a .Range command. You must explicitly add each cell together (and the autosum button is the easiest way to create the necessary formula).
- Collapse the sheet.
 - Click on the cell that will contain the total.
 - Click the Autosum button.
 - Shift-click or ctrl-click to select the cells above you want included in the total.
 - Click the autosum button again.
 - Your total will now be right regardless of whether the sheet is expanded or collapsed.
 
Try it - you'll see.