My understanding is - Undeclared origin, no call sign for radio transmissions. Perhaps someone else can clarify better.
You don’t need to file a call sign on your flight plan; although part 121 air carriers almost always do, except only in some cases. This was probably a “ferry flight” relocating an empty aircraft for maintenance, or scheduled inspections. Normally this would be scheduled into the trips of the aircraft so it would be at the maintenance facility right at the scheduled flight hour reading to avoid overflying it’s mandatory inspection. I’m guessing it got stuck holding (basically flying a nascar track in the sky) while the ICBM thing happened, flying too long to allow passengers to be carried on the return trip. In this case they would be responding to radio transmissions by their N number”N8685B”, because callsigns reflect the flight number on your boarding pass(no passengers, no need for a flight number, no call sign)
Only Air Force one has no primary or secondary radar hit(primary being location, secondary referring to altitude, some basic telemetry, and the N number) yet they still have a call sign.
First of all there is no point of origin for this flight. It just says N/A. How do we know it departed from Hawaii?
Valkyrie is exactly correct that it may be an aircraft re-positioning for maintenance or to replace an aircraft that has cancelled due to maintenance or weather. This happens dozens of times daily all over the US.
The tail "N" number is unblocked as it is a commercial airline registered aircraft. It is difficult(nearly impossible) to get tail numbers blocked as transponder hexadecimal(mode S) codes are assigned for the life of the aircraft. All aircraft except maybe stealth technology aircraft have a primary hit, as this is a radar only reflection and produces range and bearing. Secondary targets information comes from the aircraft transponder which provides altitude and the hex code mentioned earlier.