I got the answer.  Sharing it here.

The program is working to come up with the correct answer (here it's $0).  The IRS rules in this calculation are to avoid blank and negative numbers (where it says 'no less than 0').  It's how the software was programmed to comply with IRS rules. So if line 11 shows the 29200, instead of 0, it's going to have negative amounts "on line 12". To avoid having negative amounts, it stops the line 10 amount from flowing to line 11, and assigns 0 on line 11 instead. It's not that its picking line 9 (smaller amount) over line 10 (the larger amount). Line 11 just is assigned to have 0 as the value. It's really to avoid having negative numbers, and blank lines. Per the IRS rule.