Subitem Formula (sub-items_formula)

I seem to be having some issues with displaying the total amount from all subitems in the parent item; only when there are multiple subitems. One subitem is fine to display the total as a dollar value, multiple subitems as a dollar value displays an error message in the parent column.
If the formula for the subitem is a “sum” it’s ok, though when I change it to display as a dollar value instead of a number, it’s shows an error.

I am in agreement here. This would be helpful for invoicing, inventory tracking, and I am sure a whole bunch of other things!