It may have been ‘taken away’ from you. Summary is going away anyway, so people have reported the ‘pie chart’ icon at the top-right of an account view isn’t there for them anymore.
From the Bills pot ‘Left to pay’ information: “We use your Summary period as the date range.”
Which leaves you in a predicament of not being able to access Summary to change the date 
Part of me wants to say ‘Leave it until the next cycle’, so that later cycles will start to use the new cycle-end date, but I’m not sure that’ll work either.