C3422WE, macOS, DDM input shortcut keys not working

Hi,

I have a C3422WE connected to a Windows Surface Laptop (via HDMI) and a Macbook Pro 2017 (via USB-C). I run DDM on both devices and have set the Input Manager to change from HDMI to USB-C as favourite short key on the Windows laptop and from USB-C to HDMI on the Macbook. The shortcut is Ctrl + CMD/Alt + <- (left arrow)

In theory, I should just be able to switch between the two inputs with the same command. On the Windows Laptop, it always works. On the Macbook Pro it only works the first time after registering the shortcut key in the Input Manager. When I try to use the shortcut after, it doesn't react. I always make sure I click on the Desktop before using the shortcut.

Windows Laptop and Macbook Pro are up to date, running Win 11 and MacOS 12.1 Monterey. The monitor has received the available firmware update.
I have tried uninstalling and reinstalling the DDM on the Mac, but that did not help. Can someone help troubleshoot this behaviour? Many thanks!