I also have an LG C8. I used the irdb link and "LG TVs: Protocol NEC1 device 4 subdevice -1" to get the codes, but they don't work for me.

I'm using the following directions to program a spare button on a Motorola STB remote. I've done this successfully for discrete codes on other TVs:

1. Press the "Cable" button at the top of the remote to put it into Cable Box control mode.
2. Press and hold the "Setup" button until the "Cable" button blinks twice.
3. Type in the code 994. The "Cable" button will blink twice.
4. Press (do not hold) the "Setup" button.
5. Type in the code 00197. (for power off)
6. Press whatever button you want to map the code to. The "Cable" button will blink twice if successful.

What am I doing wrong?