Xiste, I just tried cmd + alt + J shortcut and it worked as expected. Maybe, you set this shortcut on the system for another task?
Cec, I looked at the differences between versions 6.0 and 6.3, and I'm really wondering what could cause the issues you encountered.
First, I tried to guess from the context what you meant by "Swedish restart"? Is it a reference to the color of the Windows BSOTD (Blue Screen Of The Death)?
Then, I tried to duplicate many large objects with the option key under macOS 10.14.6, but it never crashed even if the 3D view was slowed down (but I didn't edit the same file during hours). Did you pay attention to increase the max memory if needed? Would you have the patience to test Sweet Home 3D 6.1.2 or 6.2 too?
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Emmanuel Puybaret, Sweet Home 3D creator
