You are indeed correct. I've just had 2 customers come up with incorrect AMT. ProSeries 2019 did not do this.  ProSeries 20 assumes any cost adjustment triggers AMT (most don't). Anyone wishing to see an illustration of this can see it here:

https://drive.google.com/file/d/1V-03vVc-qPD5M-InGvg1MxWnhSkaEq82/view?usp=sharing