I'm curious what you decided to do. I have the same issue. The taxable social security changes when I enter the amount of NOL that was calculated with "taxable income without regard to the NOL".

I decided to enter "O" NOL and let Lacerte calculate the taxable income (which calculated the taxable social security without the NOL deduction which would be the "taxable income without the NOL"). Then I manually calculated the 80% limit of NOL using that taxable income and entered it into the data. Then let it recalculate the return, which recalculated the taxable social security.  I couldn't find any IRS insight into this situation with SS and NOL in same return for clarification. I hope this is what was intended.