It's still not showing up as solid black:
191372

Does that mean the setting was not applied successfully? I've restarted the computer, and it's still blue. I'm on 1803.

That's why I said it's an Optimus issue, not just an Nvidia issue. I also have an Optimus laptop (6700+1060), so I imagine it's a problem with switching between the iGPU and the dGPU which causes...

It's an issue with Optimus laptops with Pascal GPUs, and it's been unfixed since the release of Windows 10, i.e. for 3 years now. It (along with a plethora of other bugs, like random GPU spikes and...