I never heard about such a problem.
Some information that will help me to fix this bug may appear in the console.
Could you try this, please?
1. Launch Console program found in /Applications/Utilities folder and click on "Clear display".
2. Launch Sweet Home 3D and import a piece of furniture.
3. When the bug happens, console program should display some new text.
Please select that text and copy paste it in a comment here.

Thank you for your help.