custom tree shading issue

Hi there

I’ve got a shading issue on my billboards, when using the mass tree feature.
They were done in 3dsMax and exported with custom normals, created with the normal thief

It works perfectly on the tree itself but no matter which shader I use, the billboard texture is wrong, white or not displayed.
The only way to get the same result is the “soft occlusion leave” shader but it ignores my custom normals.

Is there any chance to have my soft tree shading and billboards ?
Maybe it could be fixed manualy if there’s access to the billboard texture but I can’t find it.

Thanks in advance.

Did you ever solve this? I just bought some tree’s off the asset store that are doing this