Layout 2021 will not open at all, from anywhere

[DaveR]

See this thread:

Layout not opening

For anyone following along, the appdata LayOut folder seemed to have problems. By deleting %AppData%\SketchUp\SketchUp 20201, LayOut was able to rebuild the folder, and then things were ok. We did copy across the SketchUp and LayOut plugins and templates folders across, so that the refreshed folders had the existing extensions and templates.