Date shows nil when debugging but date string has a value, is this some kind of bug in Xcode or expected behavior

Question

I'm assigning date to a variable by adding days to current date and get the string from that date like below.

let today = Date()
let duedate = Calendar.current.date(byAdding: .day, value: due, to: today)

let dateformatter = DateFormatter()
dateformatter.dateFormat = "MMM dd, yyyy"
duedateString = dateformatter.string(from: duedate!)

This works fine. but when I debug, I'm getting following issue

hope this shouldn't be the expected behavior. anyone has an idea or experienced with this and anyone knows the reason for this.