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When we use a section view, we rotate it if needed and place it in the correct position.
After an update or just go back and forth between modelspace and paperspace the view goes back to the original position.
How can I lock this view?
I suppose you rotating section view using the rotate command, right?
Instead please try the VIEWEDIT command option "Rotate view" - it allows to orient any view's segment vertically/horizontally.
The view rotated using this tool will not reorient after VIEWUPDATE.