Procedural Landscape from Shader Graph Editor | Plugin | 4.26 / 4.27 / 5.0

I absolutely want to figure out your issue, what are the settings of your world? If you can post a screenshot or your settings/your problem, would help. in wireframe mode the collision mesh should be seen in blue, while the world is grey/yellow.
If you’re making changes to the world Material function, you need to toggle ‘rebuild’ in the detail panel to update the collisions accordingly.