After making a Build the error pops up:
“Not allowed to access vertices on mesh ‘Curve’ (isReadable is false; Read/Write must be enabled in import settings)”
For imported objects I can easily enable Read/Write via checkbox.
The problem is with 3D objects I have added right into the Scene - since they are not in the project folder, they do not have Import settings.
You are probably calling Unity - Scripting API: Mesh.UploadMeshData with a parameter of false. That will also make them non-readable.
Darn. Where do I look for it? Is it at all doable?
Well, it’s something that your code, or whatever code is generating that mesh is doing.
Hell knows…
I guess I’ll just create one in Blender and import… Jesus, all this extra work now to replace them… Heh.
OK, thank you.
But what is generating the mesh?
I don’t know.
Mu knowledge of this is non-existent 
I learn on the go and this is one that’s new 
