As I've already mentioned, if you check the "Different first page" option in a document with only one section and add other sections later, then "first page" means "first page of each section". So you can lose number on one page somewhere in the middle of your document- at the beginning of each new section.
When I was working through this, I remember losing the page number on the first page, but I reset it for page 2 (I think that's what I did). Resetting the page number makes this one a bit less efficient than the linking section solution.
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