I found one instance of text on the last page.

That let me turn it off fine.

Then I did a "replace" as shown below.
00 deleteme 2.png

Then I closed and reopened the document and ran the same replace again with 22 instances replaced. Then, without closing, I ran it again and had one replace which would not go away. I determined that this was a page field in the header which is supposed to be so marked.

I closed and reopened. By the way, the text I had spotted on the third page never went back to being marked for "do not check."

I then looked at each instance using Find-Next. None of the instances were text, they were all either that field or control buttons.