Hi Wim, so unfortunately I can't seem to reproduce the problem over here - I've tried putting in various combinations of the Alt+8 dots, and multiple spaces in the folder and file name and they all seem to be working for me when double clicking the .3dm file or doing drag/drop, I tried on OS X 10.7 and 10.11.

Is there anything else that you can remember that might have caused the problem? It will be hard to fix it if I can't repeat it.

- Michael