UD3900 and UD6950 Not Working With New Computer Build

I’ve been using the UD3900 for about 5 years without issue on home and work laptops and desktops. I recently built a new desktop as follows:

Core i7 8700K (onboard Intel® UHD Graphics 630)
ASUS Prime Z370-A Motherboard
No graphics card

When I start the computer and it’s connected to the UD3900, I can only see my cursor.
If I connect the UD3900 while the computer is running, I can see the desktop and cursor, but any app I launch only shows up on the taskbar, not the desktop.
I bought the UD6950 because I thought it was a newer type upgrade and maybe would be the solution to what I was experiencing with the UD3900, but I’m getting the exact same results.

Any help would be appreciated.

UPDATE: I figured out why I’m only seeing my cursor when I start my machine when it’s connected to the dock, the problem is somehow my machine is detecting 3 monitors when I only have 2 and I’m not able to see the main screen. How do I get my machine to only see the 2 monitors connected to the dock?