I've created a forest patch custom asset and it only appears when looking from afar. I also cannot make a thumbnail in the editor as the window looks empty. The asset can be selected in BIM mode. Adjusting view properties doesn't help either nor does turning RTX on or off. The problem persists when making a standalone .exe.
The model is about 20x20x25 m in size and ~2000 triangles with 4 image maps. I've tried importing in different units and both as .obj and .fbx.
The custom asset editor is an awesome addition when it works. A total gamechanger as most of the actual asset library is not usable in Nordic countries when it comes to trees. Please prioritise improving custom asset editor to adding more content to the library.
I had the same problem ("Unabletoconvertsourcefile"). It was caused by the source geometry file (.fbx /.obj) having scandinavian/umlaut characters (ä,ö...) in the file name. Everything started working after I got rid of them