Frame to RTF paragraphs out of order

I'm on a Windows 10 OS, using Frame 2017. I have an unstructured Frame document in this order:

paragraph 1

paragraph 2

paragraph 3

paragraph 4

paragraph 5

Section head

paragraph 6

When I Save As RTF, paragraph 6 replaces paragraph 4. Then the rest of the document is fine...Section head; paragraph 6, etc.

If I retype paragraph 6, then the conversion is fine. I see nothing unusual or weird in the paragraph. Easy fix to retype but I'm wondering if there are problems in the remaining 300 pages. Any way I can narrow this down to find the problem?

DM