When I try to put my computer to sleep or hibernate, it stays on for a few minutes, and then proceeds to shut down. I have fast startup disabled, but for some reason the option to "Allow the computer to turn off this device to save power" in Device Manager is greyed out. I enabled selective USB suspending, and I did an sfc /scannow to fix any corrupted files.
It managed to sleep and hibernate a few times, but the issue returned.
Is there some way I can check which devices keep my PC awake, and ultimately result in my PC shutting down?
I'm using Windows 10 20H2
EDIT: The issue began a few months ago, so my PC was sleeping/hibernating properly for about a year. It suddenly stopped sleeping/hibernating out of the blue.
EDIT2: I have a custom-built PC, so I have no specific drivers or programs that control power. Everything is the default Windows drivers/programs/settings/etc.