Try deleting the com.apple.screensaver.plist.
You need to look in your user Library/Preferences for the .plist. Either hold down the option key while using the Finder “Go To Folder” command and select your user Library in your home folder or use the Finder “Go To Folder” command and enter ~/Library/Preferences/com.apple.screensaver.plist. Move the .plist to your desktop.
Test. If it works okay, delete the plist from the desktop.
If the same, return the .plist(s) to where you got them from, overwriting the newer ones.
If you prefer to make your User library permanently visible, use the Terminal command found below.
Show User Library
You might want to bookmark the command. I have to use it again after every update. I have also been informed that if you drag the user library to Finder it will remain visible.