Imported Models have to be opened+saved in Editor

[Rastar]

After importing models via copying them to the project folder, they can't be used right away. They appear black in the asset explorer, you can work with them (e.g. copy them to viewport). You can also assign materials to them, but they won't work.

 

You first have to open the imported in the LE model editor and save them, after which they appear greyish in the asset explorer and are working properly.

[Admin]

I've been doing a lot of work in this area, and I think what you are describing will be solved in the next update we push out.