I don't know why this happens, but I also heard that this is a common problem. There were many solutions I tried. Disable/Enable, Uninstall/Reinstall AC adapter, updated the adapter, unchecked the "Allow computer to blahblahblah" in Power Management, and maybe there were more? None if these methods worked. I tried to reset and reinstall Windows 10. It fixed the problem but all it did was downgrade back to its old version, which is fine by me...that us until it starts to automatically update itself. I do believe the update it downloaded is the Anniversary Update, which caused a lot of problems back then. It there a fix to this?