Hey, hey, I think I found a much more reliable workaround for the grey 3D view in Beta 23. [:)]
Be sure to test all kind of ways that could alter the size of the 3D view at screen: moving separators at left and top of the 3D view, changing Sweet Home 3D window size, maximize / minimize window, moving window on the screen borders to partially view the 3D view, displaying the 3D view in a separate window and changing that separate window...