We are having issues with raycasts in 2017.4 on WebGL where they will not register on some objects with MeshColliders. It's not consistent and probably affects 20-40% of objects in our entire project. We are using RaycastAll but RaycastNonAlloc does not fix it. The MeshColliders are not convex but setting them to convex fixes some of them but causes issues with some other % of objects that didn't have problems in other scenes. Some of these objects are inside of other colliders, but not all of the objects exhibiting the issue are inside of another object. The issue crops up in WebGL but not in the editor. The MeshColliders return correctly 100% of the time in-editor The issue is reported here https://issuetracker.unity3d.com/issues/raycast-doesnt-hit-some-objects-in-webgl-build but was dismissed. I can confirm that the 2018.2 beta does not exhibit the problem but we unfortunately cannot move to a beta release for a live product. I cannot share a copy of the project or rip out the problem bits due to it being the company's property but I can work with someone from Unity to sort this out.