XPS 8910, U3419W, HDMI for video, USB-C for keyboard/mouse

Hi there - I have a Dell XPS 8910 and a Dell U3419w monitor with a USB keyboard and USB mouse plugged directly into the monitor.

• Video: I am connecting the computer to the monitor using HDMI, and the video works fine.
• Keyboard/mouse: If I connect the computer to the monitor using USB 3.0, the keyboard and mouse work fine

I would like to change the setup to the following:

• Video: continue using HDMI
• Keyboard/mouse: Connect the computer to the monitor using USB-C connector on the back of the XPS

Unfortunately, the computer doesn't seem to recognize the keyboard and mouse when connected via USB-C.  Is this possible?  Here is how I have the Display Manager setup:

Thank you in advance for any help you can provide me.