NSImage does not Change for Light/Dark Appearances

Question

I am developing a Mac Cocoa app. And I have a set of images to adopt for both light and dark modes.

I followed the instructions here: https://developer.apple.com/documentation/uikit/uiimage/providing_images_for_different_appearances

In viewWillLayout(), I set up an image for a view like so:

nsImgaeView.image = NSImage(named: "Image") // Does not change after toggling light/dark mode

ButNSImage(named: "Image") simply does not change its appearance after me toggling light/dark mode in System Preferences.

I am sure that the code was invoked because:

nsImgaeView.image = NSImage(named: "Another_Image") // Changes to another image after toggling

Restarting the app does make it change its appearance. I guess it is because the system caches the image after the initial load?