July 10, 2017, 11:58:35 pm
Somewhat strange given it is just that specific combination.

There is nothing that can be set in Lumion for that. It should definitely be working OK, in other words it is not a Lumion bug.
Given it works fine with a different keyboard, then your best option will be to replace the keyboard. But just check, now that it is working, that the original keyboard still does not work. And try after a reboot of the PC, a well as plugging the keyboard in to a different port, in case there is a problem with one of the ports.