Camera positions in sketchup are independent of how you resize your modeling window, so they must be set as a view based on a coordinate for the viewer, a viewing direction, and a field of view.
That means there is a viewpoint coordinate set to the scene. For a plan view that only defines where ones plan view is positioned within ones modeling window.
In Layout, for viewports with plan views, one gets to set standard views (top) so as to define (and override, it they are not the same as the sketchup scene) the orientation. But the position will change it you update your sketchup scene after panning and zooming. Its easy to destroy ones Layout viewports if one updates the sketchup scene the wrong way. The right way is to update the scene without camera position change, but thats easy to forget. You could always have your scenes set to zoom extents so that at least you have a reference to get back to, but the extents of your model might change as well.
So if you make that update mistake, how do you get back to what you had ?
The solution is for Layout to have a “keep original camera position” or “lock camera position” option. The lock viewport option one has now is only useful for viewports that you never want to update.
I think this “lock camera position” option set to the viewport will solve other things as well. Now I untick “enable sketchup model editing” so as to not by accident orbiting my plan views. But that means I cannot change the few viewports that are in perspective. Having locked “camera position”, “ortho”, and “resize”, should mean that I cannot enter my viewport at all through double clicking it.
Together with “lock camera position” and the existing two options “ortho” and “keep scale on resize” one can make sure ones viewports never undergoes sudden changes.
After all, sometimes one does things in sketchup without thinking about the consequences to the layout viewports, and its nice to have ones brain cells focused on the modeling, and not constantly on the procedural steps of how to keep ones viewports in order.