said you should enable Show->Visualize->MeshDistanceFields to see if the trees do have a correct distance field represetation. Once that is enabled you should see a black/white view. Post a screenshot of that here. If there is no white, then there is no distance field.
Based on your screenshot, I would say there is no distance field. I don’t know if its a bug, but I’ve noticed that once you enable distance field shadows, the regular CSM shadow distance is somehow modified a bit, that’s why you probably see that the shadow distance is slightly more once you enabled it, even though there are no distance fields in your scene.