I just purchased my SP7 about a week or two ago. I've been having this same issue. I haven't really tried to identify whether it's when I'm on battery versus plugged in, but I'll definitely be paying attention to that moving forward.
For me, if I'm using the device and then stop doing anything for like 30 seconds to 1 minute, then it just shuts off. Black screen. I can hit the power button and it boots up like everything is fine, but I've lost all the windows I had open and any work
I had done. I have tried reboot the operating system, made sure I had updates done, I've run the diagnostic toolkit (no issues). Nothing has fixed it thus far.
Another issue I've had pop up a few times is that occasionally I will be working and then stop for a minute. Just like when it shuts off, except some of these times the brightness gets cranked up to 100% and then the whole thing freezes up and I have to
hold the power button for 20 seconds to get the device to shut down and then restart.
At one point, it was having some problems with the brightness adjusting a bunch (going up and down, repeat, repeat). I turned off the "change brightness when lighting changes" function and that seems to have stopped for now.
I've never had a Surface Pro and I really loved the functionality, feel, etc. Hopefully this issue can be fixed and I don't need to return it for a refund and go with a different device.
Reliability Monitor results included below.
