Dropped assignment grades still calculating

A teacher has made me aware that dropped assignment grades in one of her classes are still calculating. When reviewing her gradebook setup, I see that she has it set up to drop the lowest “Classwork” assignment grade. When looking at a particular student in the gradebook, I can see a “D” next to their lowest Classwork grade, indicating this is the one that should not count toward their marking period average. However, when I remove the “dropped” grade and Commit, their marking period average actually changes. Is this feature working as intended or is there something I'm missing?