No Thumbnail With Procedural Mesh

I am making a plugin with objects inherited from AActor.

Here’s how it’s look like

image

It’s a object with procedural mesh component as root component.

After I save it as a blueprint, it shows no thumbnail but an actor icon.

image

However, after I add a cube to the blueprint, it renders thumbnail.

image

I suppose this is a bug to do with procedural mesh.

Is there any information or confirmation about this?