Hello,
my lightkey module seems to be broken, the button U5 doesn’t create any keyboard signals. The light turns on when I press it though, so I assume it’s not a cable/connection problem.
Here’s the output of the showkey program, after pressing all 5 lightkey buttons U1-U5 one after another. As you can see, only the first four show up (U3 sends keycodes 109 and 24 together)