Were the trees placed with the foliage tool, or painted on, or placed separately one by one? There’s a few possible reasons it’s doing that I’m thinking of:
- The distance field meshes for the trees aren’t a high enough resolution / aren’t two-sided (open a tree mesh in the mesh editor, go to Build settings for LOD0 and enable “Two-sided mesh distance field” and/or increase “Distance Field Resolution” in steps to 2, 3…etc until a more fully-formed shadow is rendered)
- Mesh Distance Fields aren’t enabled in the project settings (go to Project Settings > Rendering and check “Generate Mesh Distance Fields”)
- The Global Distance Field is casting those globular shadows rather than the mesh distance fields that are generated per mesh.