Brilliant!, the model is workable now. I'll keep you posted about the success / failure of 'reloading' the model in the original scene. Then exporting to Google. Thanks.

Perhaps on the other ones, Google is using some internal optimizations to trim your model's vertex count. Maybe it can't do that on this one. One optimization might be to convert a rectangular face with several polys to two triangles, if they all have the same color or texture information. If you colored those polys differently this time around, then Google can't reduce the poly count anymore.