OS: Windows 10 Anniversary Edition

Device: Dell Latitude 11 5175, 8gb RAM, 256gb SSD, core m5-6y57

Issue: 

So for some reason my device's screen insists on staying at 40% whenever there is a change in position. 

My adaptive brightness is disabled. I've set windows 10 to not save me power when it knows when I'm away. Unlike other posts on the forums, my backlight works. I can turn it down or up.

Whenever I set down the tablet, in 6 seconds, its brightness will revert to 40%. Likewise, if I stand it up, within 6 seconds the brightness will revert to 40%

I've changed the default brightness in the power options for both the Balanced and Dell settings. No joy -- it would self-reset. Even if I create my own custom plan with my own custom default brightness, my custom settings will be over-written by the same 40% brightness whenever a change in position occurs.

I suspect a driver is over-writing my settings. What's the fix?