I'm confused at what I'm missing here. In the System Settings Screen>Login Screen>Breeze (which is active theme) I've changed the background to a custom image. But it still shows the default image of geometric shapes. When I click the icon for the background it confirms that I have my image saved for the background.
However, when I first boot up my computer, the login screen is correct with my custom wallpaper. But when I've locked my computer with [OPT]-L the screen shows the default geometric wallpaper.
