GNU+Linux Dual Panel Monitor Display Problem (Full screen on only one panel)

PROBLEM: Monitor is displaying individual panels rather than a single, unified display when using Nvidia Linux drivers. (The monitor has no problem under Windows.) Full Screen games only go “Full Screen” on one panel, the other panel/rest of the monitor is blank.

GTX 780
Nvidia 440.100 GNU+Linux drivers
Dell UP3214Q Monitor

This is a 4k monitor which is comprised of two panels inside the bezel, each a 1080p panel. You can get the monitor to work properly when using windows drivers, but when the GNU+Linux ones are used, it doesn’t unify the display into a single output. Instead, you have the panel on the left and the panel on the right.

If you go into settings, there is no display option available for 3840x2160. If the display goes to sleep, sometimes it wakes up with only one of the panels working, and the monitor needs to be power cycled.

How can this be fixed?

User’s Guide

Nvidia
https://www.dell.com/support/article/en-uk/qna43592/how-do-i-find-the-latest-nvidia-driver-for-the-up3214q-and-up2414q-4k-lcd-monitors?lang=en