Keyshot 10 move tool not working on some .bip files

[mikejb]

I have a problem with the KS10 move tool not working at all in some files. When I select a part and then click on the move tool button, the move tool appears over the part but it doesn't matter how I try to move the part (translate/rotate/scale) any attempts are ignored. It's as if the move tool wasn't even there! I haven't got any parts locked, and the move tool does work on about 90% of my other files.

Has anyone encountered this problem, and if so, is there an easy fix?