Form will not calculate on fields once approval process starts

Perhaps I'm doing something wrong, but I have this two page form where inputs are required from several users who apply their electronic signature once they have completed their part. The issue is once the form is submitted for the next person in line after the originator is done the fields that they fill in have associated fields that need a calculation to perform. For example if I have a column for the second person in line to add their inputs and sign that is for the "Quantity" and another column for that same user to complete for the "Size", then the next column is supposed to automatically calculate the "Total QTY" by multipling the first two columns together. This value just stays at zero when the second user in line adds their "Quantity" and "Size". Why wouldn't this automatically update the field next to it that has the calculation set up based on the inputs of this user's 2 columns of entries.

Please advise, SS