Cannot save comparison model

I like to use the command  "compare model" and fetch a different version from the commonspace to see what's different. Using creo 2.0 I was always able to do a save as on the comparison model in case I wanted to overlay them in an assembly. Since we moved to creo 3.0 I now get a message saying "Cannot save comparison model". Can't do a "Save as" or backup.

Anyone know if there's maybe a config option that will let me override this?

Thanks for any input.