I think the "Step To" is refering to the next level "Step" (achievable at time of 2103UTC) where the max level is refering to the "Current" maximum. The Optimum being the "Current" optimum level. Otherwise, could also have been a cockup in the Cost Index figure.
I'm guessing that you were less than 3 hours into your flight when you saw this?
Disclaimer: Haven't flown a Boeing for a long time.