Of 16 cameras attached to a Linux based DVR all cameras show on my Rapport tester at the DVR end. Only 13 show show on the DVR. 3 are black with the motion detection signal showing at the bottom of the picture.
DVR positions changed and complete DVR replaced. Same problem.
Cable runs approx. 150m, Cat 5 Cable with Video Baluns.

Try reversing the pair on one of the baluns for each bad camera.