As I explained in my post, the Max box that you have highlighted the 10 in yellow, this does not show up for me.  I’ve attached a screenshot.  When I do your other option in Lists, MAX is not an available Column to add. 

We have Multiple Inventory Sites and the Inventory Site Max works but the Global MAX is set to zero for some reason and is prohibiting me from changing it or entering a different Global Reorder Point.