CombineMeshes not working on one machine but is on another

Hi all,

I've written a fairly simple script that procedurally generates a bunch of floor tiles (simple two-poly planes) and then uses mesh.CombineMeshes() to munge them into a larger mesh.

Now this works absolutely fine on my Mac with which I originally created the Unity project, the mesh is created and displays perfectly in the Game and the Scene views. However, if I open the same project with my PC (the project is shared via Drop Box) and run, the mesh does not appear in the game or the scene window and no errors are thrown. The strange thing is that it does appear in the hierarchy, and when I select it and double click the mesh entry in the Inspector it shows the right number of vertices and tris.

If I remove the CombineMeshes part of the script and simply use a single one of my procedurally generated tiles as the mesh, it works fine - this leads me to assume its a problem with the CombineMeshes method.

Both the Mac and the PC are running Unity 3.4, and the project files md5 against each other on both machines so its not a corrupt file either... any idea what might be causing this?