Sometimes the front lights are on and none of the others are. Since I did not hit the button to turn the fronts on 1 of 2 things happened. The motion detector 'saw' motion, sent a signal but only the front lights paid attention. And somehow the RR501 did not itself trigger.
Or some kind of spurious signal caused the front to turn on but the others did not.
When you begin troubleshooting your noise or phase coupling problem or possibly Smartmeter problem, it will be helpful to understand how X10 works.
The X10 wall switches, Appliance Modules, and Lamp Modules receive their commands from the powerline, not RF or wirelessly. When the motion sensor sends a RF command, it is the RR501 that picks up the RF command and transceives it to the powerline for the wall switches to act on. So still not sure what you mean by "And somehow the RR501 did not itself trigger." Unless the motion sensor has a Unit Code of 1 or 9 the RR501 won't make a peep but it appears to be transceiving properly. Plug the Mini Timer in to same outlet as the RR501 and turn the lights ON with the Mini Timer. If the same light comes on, and the others remain off as they have before, you likely have a noise or coupling problem between that outlet and the circuits the other lights are on.