Laptop doesn't turn off the screen or go to sleep when inactive

Hello everyone,
so just the other day I (finally) upgraded my Lenovo Ideapad Z510 from Windows 8.1 to Windows 10. So far, I'm pretty happy about it, so I'm definitely not regretting it, but there is one thing that it's starting to frustrate me.

Basically, when the computer is idle, the screen doesn't turn off after the set amount of time (I have it at 5 minutes on battery, 10 minutes if connected to the AC charger), and the laptop doesn't go to sleep either (it should do so after 10 minutes on battery, 30 minutes with the AC charger). It's really annoying, and I can't figure out why. I have tried to change the settings, disable apps and programs and such, but nothing has solved the problem so far.

After looking it up on google, I read about people who had this issue and apparently it was caused by some USB gaming controller connected to the computer. I have no such thing though, the only USB device I have plugged in is my wireless mouse (Logitech). I did try to remove it in case that was the problem, but unfortunately nothing changed: when inactive, the computer still doesn't turn off the screen nor it goes to sleep.

I have noticed that if I leave it idle for a while, say 1 or 2 minutes, at one point the brightness decreases slightly for, like, less than a second, and then it goes back to normal, as if someone touched the mouse to "wake up" the laptop (but clearly no one touched anything).

Did this happen to anyone? Any idea about what could be causing it? So annoying. Could it be a driver issue, or maybe some software running in the background?

Any help would be greatly appreciated. Thanks!
V

Maybe too obvious but have you chosen the right "Energy Profile"? I once set up a custom balanced profile then came to the conclusion the default profile was still active.

I don't think I've ever changed it to a custom profile actually. Anyway I even tried restoring default settings just in case, but the problem still remains. Also, I have installed the most recent ACPI driver from Lenovo to see if anything changed, but no luck so far...

Don't mean to keep pushing my suggestion but I hoped you at least looked at ur current schematic under powermanagement right? Could be the upgrade somehow messed things up.

Also the correlation between either Win powermanagement and/or UEFI settings could be a factor. Don't know how this works for your laptop but could be worth a shot as well (as far as you haven't done so already).