Ok, there is certainly an explaination. I was driving off Hwy 1 at the Pebble Beach exit - where they were running the golf tournament today. A parked CHP unit that was left with its forward Ka radar running C/O was parked at a 90 degree angle from me, to my right facing away as I sat at the stop sign. The CHP car was literally 50 feet from my vehicle. There were 3 officers standing around (traffic control for the tourney) and once I made the right turn and got adjacent to the CHP patrol car, the Redline went full tilt.
Although this was off-axis, facing away, it was the first time I've been so phyiscally close to a radar unit without a detect. My explaination is that in front of the CHP car was dense tall trees, and I am pretty sure (based on previous experience) that trees 'eat' radar, and nothing comes back.
However, it was a little odd for this unit that has picked signals from more than 3 miles, that it could not get a sniff of the CHP, close enough I could hit it with a rock, underhand.
It was also the first time I ran with the new single-suction mount. I know off-axis has to take a hit with this, as it sits so far back from the window. My windshield is slightly 'bubble' shaped, and when pressed against the window, it can easily see sideways, whereas now it is blocked from the roof pillars.