I am trying to build a landing page and want to replace the wallpaper image source. The new image is also a png and has the exact same dimensions, but it just shows as blank?
That's not enough enough information for us to act on, Olivia. You'll have to show your HTML source code and screenshots of the LP Editor behavior (we don't even know if you have a Guided or Free-Form LP!).
If posting code please highlight it using the Advanced Editor's syntax highlighter so it's readable: