1. Here's why
1.1: An external USB or Bluetooth input device such as a joystick, tablet pen or a game controller (e.g. Xbox) is interfering with the navigation controls in Lumion.
Please disconnect those input devices and check if the problem has been resolved.
If you're using a Leap Motion device, you must unplug it and restart Windows.
1.2: If the Enable Tablet Input toggle button on the Settings screen is turned on, please turn it off if you are not using a tablet pen.