Optimal Lineup discrepancy?

Ive have Auto-Pilot activated through the site, but when I go to Matchup, my Optimal lineup will be different than what the Current lineup is… so why does Auto-pilot not set the lineup thats shown as Optimal ? example: This week Auto-pilot set Kamara, Henry and Keaton Mitchell in my flex, but Optimal lineup shows Kamara, Henry and Brandin Cooks as flex, so I changed my lineup on NFL Fantasy to match Optimals suggested players, then I got an email saying Auto-pilot changed my lineup, and it benched Cooks and put in Mitchell. Can anyone explain why it does that ?