If LayOut lacks sufficient system memory to display SketchUp models, LayOut will represent SketchUp models with a gray box and a red x (see example below). The SketchUp models and their contents will still be preserved in the LayOut file, even though they aren't displayed.
There are two ways to work around this issue:
- Click File > Document Setup.... > Paper and change the Rendering Resolution Edit Quality to Medium or Low.
- Restart your computer. When you log back into your computer, launch LayOut and no other applications.