Understood. Number 8 controls 14 led bulbs in landscape lighs.
I changed it to code 7 earlier, and they came on as well.
OK, since you've changed the house and unit codes for testing I think it's fair to say that the MT14 is not the source of the problem. That takes us to the switch and the load (the LED bulbs). Another controller could be sending spurious codes but since you've changed the codes on the XP3 that's pretty much ruled out too.
Are the LED bulbs powered by a transformer/power supply or wired directly to 120 volts?
Is the XP3 controlling an outlet or hardwired circuit?
If the landscape lights are plugged into an outlet controlled by the XP3, then I'd unplug them and plug in a plain old lamp with an incandescent bulb and observe.