I have a 2018 Surface Pro 6 (i7, 16GB RAM, 512GB SSD), and I have had two devices emulate the same symptoms. I have seen the issue happen with both Builds 1803 and 1809.
To reproduce the issue, I can let the tablet go to sleep (any which way), and come back to it after at least 30 minutes. Come back to the Surface, and go to turn on the screen, and it wakes up as if I turned it off entirely.
At first I thought it was something to do with my sleep settings, so I made sure that they weren’t as aggressive as Microsoft tends to have them by default.
After going into Event Viewer I see this error message, “The system firmware has changed the processor’s memory type range registers (MTRRs) across a sleep state transition (S5). This can result in reduced resume performance.”
I’m beginning to wonder if there is a huge problem with the Surface Pro 6. Anyone else know about this issue?