Running the following macro, which will convert the EndNotes to "textnotes" may overcome the issue. (Run it on a copy of your document)
Code:
' Macro created 29/09/99 by Doug Robbins to replace endnotes with textnotes at end of document
' to replace the endnote reference in the body of the document with a superscript number.
'
Dim aendnote As Endnote
For Each aendnote In ActiveDocument.Endnotes
ActiveDocument.Range.InsertAfter vbCr & aendnote.Index & vbTab & aendnote.Range
aendnote.Reference.InsertBefore "a" & aendnote.Index & "a"
Next aendnote
For Each aendnote In ActiveDocument.Endnotes
aendnote.Reference.Delete
Next aendnote
Selection.Find.ClearFormatting
Selection.Find.Replacement.ClearFormatting
With Selection.Find.Replacement.Font
.Superscript = True
End With
With Selection.Find
.Text = "(a)([0-9]{1,})(a)"
.Replacement.Text = "\2"
.Forward = True
.Wrap = wdFindContinue
.Format = True
.MatchWildcards = True
End With
Selection.Find.Execute Replace:=wdReplaceAll