Power button does not trigger suspend (nor anything)

I would like to set the power button in my laptop to initiate suspension. Note that I can trigger suspension by closing the lid, or using pm-suspend, so the problem is the button, not the suspend process itself. I use Gnome, and through the tweak tool I have configured that I want the system to reboot, so this is also not the problem.

The problem seems to be that the system does not realise that I'm pressing the power key. The most clear indication that this is the case is that unlike when I press the buttons to control the screen brightness or the volume, acpi_listen returns nothing when I press the power button.

To provide further details, I have a Lenovo Thinkpad X1 Carbon (3rd Gen) with Suse 13.2.