Each cross-references makes use of a hidden bookmark that encloses the cross-referenced paragraph. It has been noted before that moving around headings in the Navigation pane messes up the bookmarks. What you have seen is probably part of that same bug. :-(

In addition, be aware of the following (which is by design): In the main body of the document, if you add content, or a new paragraph by pressing Enter, at the beginning of a bookmarked/cross-referenced paragraph, the bookmark expands to include the new content. Therefore you must always add content at the end of the preceding paragraph instead.

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional