It looks like this fixed bug, but probably a little different.

Please send [url=mailto:[email protected]]me[/url] your Sweet Home 3D file or/and try this:
1. Launch Console program found in /Applications/Utilities folder and click on Clear display.
2. Launch Sweet Home 3D and open your file.
3. Console program should display some new text that will help me a lot to guess your issue. Please select that text and copy paste it in a comment here.