DirecTV Remote and LG C1 Television- How to Switch Inputs

I just bought a new TV, the LG C1. I was able to connect the DirecTV remote to work with the new TV, but the button that allows you to switch inputs (between say the DirecTV box and a game unit and a Apple TV or Roku) does not work. The remote does turn the TV on and off and control the volume properly, so it is properly connected.

The only ID on remote says RC73 on the top left just above the ON button. The button that should control the input switching is on the bottom right, has "ENTER" printed on it and has "(input)" printed just below it. It also makes the mini program guide appear.

Am I missing some extra step to connect the remote to the TV?
Does the remote not handle input switching with the LG C1 for some reason?
Does some other button or combo) do it instead?

Thanks.