To respond to my own original post . . . On examining the mentioned layout I see the footer is missing. Also I see that it's not possible to lock parts as you can objects. The amount of "shift" could easily be accounted for by the deletion or absence of the footer. So . . . one problem explained. Now if only I could figure out what happened to the footer since I'm quite sure I didn't delete it, and a warning message pops up when deleting a part, so it's not likely to happen accidentally.
You won't see a warning message for deleting a part unless there is a layout object in the part that will also be deleted when you delete the part.
Yes and thanks Phil,
There were objects in the footer part. Otherwise, especially for a print layout, I would not have had a footer. Good point 'tho . . . people often have empty footers because they're created by default in many layout choices, and there would be no warning in that case.
Thank you for your posts, and I apologize for the late reply.
I also get frustrated when problems are intermittent and you can't be reproduced at will. I don't see any previous case where the footer is arbitrarily removed/deleted, so that adds more to the frustration.
If you see this happening again, please keep me posted. Also, there is a chance this layout is damaged, so if you see something strange happening with this same layout, consider rebuilding the layout. Or, if you have a backup where the footer displayed, you may want to consider using the backup and move the data into the backup.