Is this by design? Tilemaps and SpriteShapes don’t have a preview when inspecting them in the project view.
A little annoying when I have a bunch of tilemap prefabs and unable to see what their contents are without opening 
One of those is a somewhat new addition, and SpriteShape is a very incomplete addition. I wouldn’t be surprised if having previews just wasn’t their top priority, since they are planning to continue to change and add things to them in the near future.
As for your issue, I suggest possibly making optimizations to your naming system so you know what things are only by the name, not requiring a preview.