I like ADS-B Exchange and all for being a (purportedly unfiltered) data stream based off community volunteers uploading data from SDR stations (I even briefly ran a data source), but it's missing data for the middle of the flight.
They heavily censor their feed. Not only for military aircraft, but they also have a service where you can pay to have your aircraft hidden by the system.
Personally my beef with them is that they started as a paid app, then transitioned to a subscription model and left everyone who bought the app hanging.
It's called "Estimations", and is in the Visibility tab of Settings. By default it will show up to 4 hours of estimated positions.
I can't say whether that's what was shown for this flight or not, as it won't show historical data for SPAR19.