I assume the Plusspec team are aware of the following issue:
Layout 2021 - Viewport Issue -- https://forums.sketchup.com/t/layout-2021-viewport-issue/150648/50
note you will need to read through to the bottom of the thread to realise the issue has nothing to do with Skalp or any plugins, and is indeed a SketchUp core problem.
The symptoms of the bug are that random section planes get turned on in your PDF outputs from layout (sometimes the layout file shows the problem, sometimes it only appears on export to pdf)
The current workaround is to track ALL properties on ALL scenes in order avoid the viewport issue. This obviously is very annoying.
What are your recommendations ?
Should all plusspec users stay on Sketchup 2020 until it is resolved ?