The numbered items in my document (146 in all) have been working fine for a very long time, except for an occasional 'Error: Reference not found' error when I press F9 to recalculate the references, and those have always been fixable by simply re-adding them. But now I inserted a new item 1, and when I attempted to reference if (via References > Cross-reference) it inserted the number 2 instead of 1. When I Ctrl-Click that reference, it goes straight to number 1 as it should, but it still shows 2.

Also, a reference to a number 9 elsewhere in the document gave an 'Error:Reference not found' error when I pressed F9 a while ago. And when I re-inserted it (via References > Cross-reference as usual), it entered number 13. The real reference to the real 13 goes to the real 13 as it should. And the reference to number 9 (mis-labeled as 13) goes to 9 as it should. But it still says 13, and when I try to re-insert any of these numbers (via Insert > Field > Listnum as always) it keeps making the same mistakes, labeling reference 1 as '2' and labeling reference 9 as '13'.

When I view this via other 'Views' like Full Screen Reading the mistakes are still there.

Any ideas as to what could be wrong and how to fix it?