Make a new copy of the document (using windows, if you can’t do it in word).
Are there any tracked changes? If so - accept them. Endnote8 and tracked changes don’t play nice with each other. If that doesn’t fix it…
if you can, unformat the document (don’t “remove” endnote fields, just return to bracket non-CWYW!). save it to a new name. Then delete the references, if there are any. With Paragraph symbols showing (button on word toolbars which looks like a P with double upright). Copy everything but the last paragraph symbol to a new document. Now try to reformat.
If that doesn’t work and you have been able to unformat the document, try removing all field codes (ctrl, shift f9). repeat above copy past to new document.