custom scaling level not initializing sometimes

I'm running a 4K display at 3840x2160 so I've set my custom scaling level to 150%. Once in a while when I wake the system up and unlock my session the icons are shrunk (probably down to 100%). If I log out and log in again I'm back to normal. I notice the settings dialog warns that setting a custom scaling level is "not recommended". What am I supposed to do instead?

some relevant system info:
GeForce GTX 960
Asus PB297Q 4K display

Ah, my display driver is way out of date. I disabled Java, and that in turn disables NVidia Experience, so I wasn't getting the normal updates. I will post again if the problem persists, but I would think this will fix it. My old driver was version 364.something.