Looks like the Poliscan was set up quite low on the tripod. When the beam hits you in the back at 10m (33') its' still very narrow, and probably hit below the license plate or on the rear bumper (LI heads are above the rear license plate). Without maximum sensor senstivity, you get failure to detect, and PT even before the jammer can fire. The LI poliscan algo works very well, but can't do its job, if it doesn't detect in time.

Poliscan only needs 10 consecutive pulses for a speed reading, and at 100pps, that equates to 0.1 sec speed aquisition time.