Now that's strange. Although I do the same thing (uncheck everything but export as MT), it makes no sense to me why having the other boxes checked would be a problem. All that the other boxes do is add different flavors of group names to the exported .obj. That stuff should be ignored when the MT is applied. The only other option is the weld but even that shouldn't cause the problem you where having. Hmmm ... may have to look into this one.