I assume you mean the LG Magic Remote? It doesn't operate RF / Bluetooth devices (aside from the TV itself). That can be an issue with a very small handful of devices that a Harmony remote would be able to control. Luckily, that's a non-issue for you, because your Harmony remote is IR only.
The remote control works very strangely, as best I can tell it actually communicates with the television to figure out the IR signal to send out to peripherals and it never learns anything itself. I know this because the TV has a built-in on-screen remote control for all of the devices you tell the TV about. You can push a button on this on-screen remote, but it won't do anything unless your magic remote is pointed at said device. This is in contrast to Samsung's equivalent system, my F8500 has a built-in IR transmitter on the TV itself.