Adding 2D PNG to Reality Composer Pro

I've got a couple 2D PNG assets that I want to add to a scene made of a couple other udsz files in RCP (picture adding a couple 2D videogame characters to a simple 3D diorama).

When I try to drag the PNGs to the workspace or the file tree…nothing happens.

I found a walkthrough on Medium (called "Importing and Exporting Personalized Objects for Augmented Reality: Reality Composer and SwiftUI" for those curious as I can't link to Medium posts here) that makes it look like users could do this with simple drag-and-drop. The Medium post is from June 2023, and in the screenshots RCP visually looks a lot more like Reality Composer on iPad, so I'm assuming it's changed a lot since then?

Is there still a way to do this? I've tried adding the 2D elements to a scene with Blenders "import images as planes," but I'm getting weird halos around them and was hoping RCP could make the process a bit easier/cleaner.

Adding 2D PNG to Reality Composer Pro
 
 
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