Issues with tree prefabs - unsure if prefabs or graphics are the issue

Apologies in advance for the noob question.

Got the prefab in the asset store of trees. They seem fine in the scene until I use them.
I’m using VR ( Rift), and from the Scene perspective trees look normal ( when being viewed top down )
However, for this program, I want to look up at the trees in VR and when I do that they stop rendering the leaves and the shader - they look like green skele-trees.

I’m not sure if this is an issue with the model, the graphics for the model ( shaders?), or VR…but all my other environments are fine, it’s just these trees that are not being cool.

It could be that the leaves are one-sided (i,e, they could have a top and no bottom). Unity’s regular shaders will typically only render triangles that face toward the camera. In that case you’d need a special shader that has this feature turned-off. Then it will render the geometry regardless of how they are oriented.

I’m pretty sure that Unity has a one-sided foliage shader for the Built-in renderer (might be in one of the old Standard Assets packages. I can’t remember). If you’re using URP, you should just be able to make a standard-lighting-model shader in Shader Graph and simply turn off back-face culling.