I did a 1040-X for extra income and got a second sched SE. The new one shows 142,800 on line 8a, the original SE for my wife is blank on 8a. What could cause that?

If I go back to my original 1040 and access Schedule SE line 8a, it has a drill down button. That takes me to my W2 which shows 142800.  Also line 8a will not allow me to update.  Are there situations where you do not use the 142800 from your w2 on line 8a?  Seems odd, the new schedule SE from my extra income uses the 142800 max on line 8a and fills that in on line 8a but the original SE for my wife's income does not.  What am I missing? seems it should be the same on both Schedule SEs.  Thank you