Connecting my MacBook Pro with a USB-C cable on both sides did not work. I therefore bought a USB-C-HDMI cable (https://www.digitec.ch/de/s1/product/roline-usb-c-auf-hdmi-1m-midrange-video-kabel-11615210) and it worked without any problems.

Hello, the cable supplied for connecting the monitor is not USB-C.
I bought a USB-C - HDMI cable, which didn't work (but I have a Dell). Then I bought a USB-C to HDMI converter and used an HDMI-HDMI cable to connect to the monitor. That works.

Note: You also need to buy a power converter (EU to CH) for about 6 Fr. The power cable is EU standard and the connection to the monitor is a rare version used somewhere in the EU. Galaxus does supply a CH flat cable for power, but you cannot plug this into the monitor.

But the monitor is cheap and really highly recommended.