Yes, apparently it can still happen, with the latest 3.858 version.
I was on the highway when my V1 started sounding Ka ahead, which gradually got stronger. It seemed more like a real threat than a Crapra, so I slowed down accordingly. Once it got to about 6 LEDs of strength, the V1 Jed out the threat. Shortly afterward, I spotted a state trooper in the median. I power-cycled the V1 and it started alerting to the trooper again.
I've had many encounters with real Ka threats (mostly 35.5 Decatur/Kustom units) and none were ever Jed out. This one was a state trooper, and they use Stalkers. I've never had any other Stalker (including my own ATR) junk out my V1 either.
I bet it happens in unusual circumstances if a junk detector is nearby during a real threat. I think if VR can't fix the problem perfectly, they should either continue alerting after the "J" or defeat the J if the signal strength exceeds, say, 6 LEDs.