Materials and meshes disappear


I’m sorry that this has to be my first post (as far (as I can remember) but I’ve a problem which I can solve, I tried looking it up in Google but without result.

So I downloaded the vegetation pack from a staff member here, sadly I can’t remember his name (the same problem with some other assets).

So when I drag a tree in my level the materials of it just disappear and it becomes a grey transparent looking object

When I double click on it in the content browser and drag the materials to it the material become blank as well

I hope someone can help me


I have the same issue!