Still outside the range of ATC radar. The point is that radar sets do not track objects outside the performance envelope they are designed for. Fighter aircraft’s airborne radar is highly optimized to target other warplanes, “UFOs” would require IF bandwidths and tracking filter process noise that would degrade performance against targets of interest.
OK, you must know more about the new AN/APG-65 radar than the pilots that use them - and more than the SPY-2 radar people on AEGIS ships - as they would have the same problems you ascribe to fighter radar, yet somehow they can track them also - a conundrum.
Or your comment was not clear to me
AN/APG-73 correction - the version which replaced the 80s AN/APG-65
I worked as a radar engineer at Raytheon for 35 years. I probably know more about radar phenomenology and principles than almost any pilot, and more than most radar engineers. Sorry but extraordinary claims, observations of extraterrestrial spacecraft, for instance, require extraordinary evidence.
Anomalous propagation, electronic glitches, operator confusion, teething problems with new systems are infinitely more plausible than UFOs.