Missing Flights DAL 179 Amsterdam EHAM To Portland KPDX


I have been tracking the daily Delta flight DAL179 from Schiphol to Portland for several weeks now as we fly on this route on Monday 18th June. I have been able to track the flights every day accept for some reason the flight on June 12th and again today June 16th currently being flown by N819NW was not shown at all on the day of the flight?

The data for the June 12th flight only appeared today even though I was able to track both flights on Plane Finder & Flight Radar ADBS systems.

Is there a reason I am not aware of why a regular flight is not recorded on Flight Aware even though it is taking place?