ENDNOTES: unable to insert new endnotes into existing section of endnotes

[sainatees408252]

Hello,
I am revising an existing InDesign document (book) with a few hundred endnotes.
Problem is that I am unable to insert new endnotes as part of the existing endnote section.
When I make a new endnote, it starts as number 1 and creates a new sections of endnotes.
I am using the latest InDesign with Win10 Pro.
Many thanks! 

[Creamer Training]

My first suspicion is that the original ID document was creating without importing the endnotes as actual endnotes, but simply text.

This could be due to:

• an error upon importing external Word file without endnotes being selected,
• the ID document was created before endnotes became a feature, or
• a script was used to convert footnotes to endnotes (related to ID not having endnotes at the time).

[sainatees408252]

Thank you. None of the three scenarios apply, but I will investigate the possibility that your core theory is correct.

[sainatees408252]

Actually, checking back before me, I think your "improper importation" theory is likely. 
Thank you!