XPS 9320 brightness changes constantly

The brightness on my non-touch, 1920x1200 panel constantly changes.

This issue has been been happening on and off for a few months; however, the frequency has dramatically increased recently, to the point where it is very frustrating to use.

I have had "auto-brightness" and "change brightness based on content" turned off, and I have never used it in the past. I have also turned off "display power saving" in Intel Graphics Command Center. The power plan is set to "balanced", and the laptop is usually used when plugged in.

Issue: the brightness of the screen changes regularly, without any input from me, or the brightness indicator popping up on screen. It will either get very dim or very bright, always rapidly returning to a fixed value during each episode even as I try and return the brightness to my desired level. This is incredibly infuriating. 

This issue does not always occur, but is now far too frequent, occurring on and off every time I use my laptop.

Sometimes nothing happens when I try and change the brightness during an episode, until I hit the windows key, a temporary fix which I accidentally discovered. The correct brightness level will then return, and usually stays for a few seconds, before the brightness begins changing constantly again.

I have tried numerous fixes, disabled all of the auto brightness features that I am aware of, updated the laptop and drivers numerous times (this is not a recent issue, just worse now), and even did a full factory reset.

I would greatly appreciate any advice or insight into this issue.