Hi together,
I'm using the menu dialog, not the context menu, for converting endnotes to footnotes. Scope: Selection

The result is not as expected.

3 out of 7 endnotes were not converted to footnotes.
1 additionally was converted, but the corresponding endnote was not removed.

Trying again with a different selection of the remaining endnote texts:
Now the first endnote could be converted, I assume because I selected all the endnote text. However the remaining endnotes couldn't be converted.

All the details can be found at the Adobe InDesign Forum:

I am showing all this in more detail at the Adobe InDesign Forum and at InDesign Prerelease as well. Together with a link to my test documents.

[ CC-2019 and 2020 ] The Convert-Endnotes-To-Footnotes Disaster SCOPE: SELECTION
Laubender
https://community.adobe.com/t5/indesign/cc-2019-and-2020-the-convert-endnotes-to-footnotes-disaster-scope-selection/td-p/10936519

Regards,
Uwe Laubender
( ACP )