Update for this. I've booted and tested the function keys for LCD brightness during the bootsplash and they work. Once X/KDE has loaded it no longer works, so it appears to be something in KDE not allowing it too work.
Update for this. I've booted and tested the function keys for LCD brightness during the bootsplash and they work. Once X/KDE has loaded it no longer works, so it appears to be something in KDE not allowing it too work.