Plane landed an hour before actual (IFR cancellation on gnd)

On this flight back in December I didn’t cancel IFR until we were on the ground at KIOW, but the arrival time shown is nearly an hour earlier than when we actually landed (and live tracking indicated we had arrived at that time too when someone checked while we were still in the air), and the tracking data drops off at that point, too. I’m sure we’d have still been in radar coverage of Chicago Center despite being controlled by some smaller approach controls. Why would this happen?

flightaware.com/live/flight/N969 … /KABR/KIOW

Thanks.