I hope it’s ok to come back to such an old thread, but I’d like to highlight that although this method generally works, I have noticed an instance where it doesn’t work.
In my (very long) document, I am indexing footnotes as I go along, by inserting entries into the footnotes themselves, ie, at the end of the document. When I reopen Index Manager (not every time, so possibly only after export, I can’t remember), and I sort by No. column in reverse, the footnote entries have been re-numbered and now appear at the top of the list! So in a very large document with lots of footnote entries, it can take considerable time (and energy) to trawl through and find my place again.
Is there any way of avoiding this, other than remembering to perhaps put a ‚aaa‘ entry in every time I have a break?