The problem is with the multiple-product control. The classic two-input multiplier control works fine.
The units of the wire hooked to the first input (top element of the resizable box) are multiplied twice (i.e., squared) The rest are handled correctly.
The fix is to make sure that the wire going into the top element has no units.
Thus rewire the control appropriately: If all the wires have units you need to add a new element on the top and wire a 1.0 constant to it.
If you are only using two inputs then you can replace the control with the classic 2-input multiplier.
