Grey vegetation

hi everyone,

When i want to drag and drop a tree (exemple) he was grey :
But in the content browser he have an texure

I’m use this pack :

Sorry if there are mistakes i’m french

This is a total guess, but what if you press the Build button in the editor? Also, if you open the Materials does any of them show any errors? Sorry, I have no better idea for now.

Open the mesh asset and check that it’s okay. The preview thumbnails aren’t realtime, they’re just static images generated some time in the past.

That not work.

And if i test with another pack that not work too, but if i downolad an plugin with the epic games application that work.