Magic keyboard functional keys (F1-F12) does not work.

I recently bought a new magic keyboard to my Imac (running on OS 12 Monterey). None of my functional keys (F1-F12 controlling sound, light etc.) are working. I have re-installed, connected with usb-c, but nothing works. Checking settings does not even include options to enable/disable. The keyboard has no "fn" key. Any suggestions?