U2723QE, switch mouse and keyboard dongle with KVM

I have a DELL U2723QE monitor and I'm trying to use the built-in KVM. I'm connecting the monitor to two devices as following:
- DisplayPort in: Mac mini
- USB-C port: Macbook
I have installed the dell DPDM app on both devices, and I have set up the USB KVM and a hot key to switch between devices. I have also connected my mouse and keyboard USB dongles to the USB ports of the monitor.
When I use the hotkey to switch between monitors, the switch works properly and the monitor receives the image data from any of the actively connected devices. But the mouse and keyboard doesn't switch, and mouse and keyboard only work with the device that's connected via USB-C port (Macbook in this case).

What should I do so the monitor will switch the connected mouse and keyboard to the actively connected device as well?