U4919DW, KVM, USB hub device disconnect issues

I have a new U4919DW monitor that is replacing a previous U3417W. The monitor is connected to my Surface Laptop 3 via USB-C connection. I have several peripheral devices hooked up to the monitor's USB ports so that I can leverage the built-in KVM/USB hub, including a Logitech Webcam, Plantronics Headset, Dell USB-Speaker, and Logitech wireless mouse dongle. 

The issue I am having is that when I use multiple peripherals at once (e.g., webcam and headset), the USB devices will suddenly disconnect. For example, I am able to start a video call (e.g., Zoom), but pretty quickly thereafter the headset will suddenly go dead, or the camera feed will blink out, and I get a bunch of notifications from Windows that devices are disconnecting and reconnecting. When not using these devices, but otherwise having them connected, I do not get any random disconnects. It is as if the built-in USB port is becoming somehow overloaded and causing device disconnects. 

NOTE: I have the EXACT SAME devices connected to the EXACT SAME computer (via the new monitor) in basically the EXACT SAME way. This all worked correctly with the former Dell Monitor (U3417W) and with a monitor before that as well (U3415W). So it's not a computer issue, peripheral driver issue, etc. When I swap my old monitor back in, it works fine. Incredibly, Tech Support actually asked me about a network firewall as a potential solution. 

Also note: it also does not appear to be a physical issue with the monitor. As Dell sent me a replacement monitor and I get the exact same problem. Both the original and this monitor are upgraded to the latest firmware. The former monitor was on MSB103 and this monitor came with MSB104.

I have called Technical Support and wasted an incredible amount of time being told how to plug in a USB-C cable, etc. One thing Dell Tech Support seem to be confused on is the fact that when using USB-C as a connection, you cannot ALSO use a USB 3.1 upstream port. The monitor's OSD will not allow pairing the USB-C video input with either USB upstream port (1 or 2), it can only be paired to one of the video-only connection types, such as DP or HDMI. 

I don't know what else to do now that I've wasted hours and hours on this, but would really appreciate any actual technical assistance. I don't think I can return the monitor at this point, unfortunately.