I have a casting models that we need to add shrink factor to and I have had a couple instances lately where they do not scale properly. One model was created in W4.0 and I had to redefine some rounds to make it work. Another part was a step file that came in with no issues but when I tried to scale it all the surfaces seemed to split apart making it unusable.
Try making your part "resolution" from the standard 0.0012 to something like 0.003. The grainier resolution may assist your surfaces from loosing connectivity. It is not perfect but it may help you work with this geometry. This command is under "setup".