When the stealth bomber was top secret and still being tested, most of the army, air force, and navy was unaware of it. Something flying at such a high altitude was considered impossible. Naturally, Air Force fighter pilots were some of the first to observe it, and some of those pilots wondered out loud if it was an alien encounter. No one at Area 51 corrected them. So, this could be a similar scenario. It could even be the case that those working on this unidentified flying object did not know the new radar tech was being tested. The many branches of the DoD are not as coordinated as they may seem.

I still don’t believe there was unassisted visual confirmation. And if they are using combined radar imagery, it seems that much more likely that a glitch in one radar system would cause a glitch in all systems. Then again, I’m heavily speculating.