Can't program key

Hi! I'm trying to teach my Sofabaton X1 to use the "Last" button from my FiOS/Arris Cable Box remote. In the app, I reach the screen where I'm instructed to hold the remote perpendicular to the hub and press the "Last" button on my FiOS remote, but it just never finishes learning. Is there another way to teach the X1 this command? Thank you!