Generally speaking a "works now, fine" and not "then" is a strong indication of either a "noisemaker" coming online (this can be hard to figure out) OR, a lack of bridging between the two legs of a 240 volt system. Things that will make it work in the latter are virtually any 240 volt appliance coming alive.. dryers, ovens, stoves etc are obvious. A frequent one not often thought of is an electric hot water heater.
If you have an electric oven or stove, when it will not work, turn either of them on and see if it works. That can verify or eliminate the phase issue.
Next step if that does not do it, (and you can verify a non-op condition exists at that point in time)and assuming your significant other will not object to resetting every clock in the house, is to find the circuit that your controller is feeding and turn it on....so you are "online". Once you have verified that, find a circuit that a device you are worried about is on, and turn that on. You will now have 2 circuits energized. Verify proper operation of your questionable device.
NOW, start turning on breakers one at a time.... until the non-op returns. The last breaker that tipped the cart will house your noisemaker.
Keep us posted.
Chris
ps. I will note that X10, much as I am a devotee, in general handles flourescents and LED's in a variable manner based on the mfgr of the lighting device. Some work, some not so much. It took me a while to turn my house into a "compliant" LED house and eliminate the X-10 issues.