Text Properties, Auto Size S’abonner

Hello all.  When using auto size text formatting in a paragraph style text field, it appears BarTender isn't maximizing the possible text size.  I attached an example and noted the following: when I set the range from 8 to 20, it chooses a smaller size than is necessary.  When I adjust the range from 12 to 20, the same text clearly fits at 12.  Am I missing something?  Thanks for your time in advance!