Layout scale change appears to bring in a previous version?

Hi When rescaling a model in layout ( which I have copied and pasted from another layout page) gets additional lines in model that have been deleted previously.

The issue is complicated further as I am getting read only error when trying to work between SU and layout - so I have to rename the file and save as something else each time I send to layout.
I am convinced an earlier version of the layout drawing is being pasted as I definitely do not have this line in my model.

Has anyone experienced this and the read only error and can advise as it is driving me crazy!

Are you creating a scene in sketchup and saving it immediately prior to sending it to layout?

Yes I think I am

You need to be aware of the references in the LayOut document.
If you have one model to present, the initial ‘Send to LayOut’ would be enough, no need to send it again to that document.
Copy the viewport in that LayOut document and set it to display other scenes (if you have the latest version, you can also toggle tags on or off)
Don’t use the ‘Send to LayOut’ feature to get different Views in the LayOut doc, set up a scene in SketchUp and just save the file.
Then, back in LayOut, take a copy of a viewport, rightclick to update the model reference, and set it to the just created scene.