This is it, voila! That makes perfect sense and is consistent with the behavior I noted earlier, that if you're early in a chapter with a ton of end notes, it navigates. But the last few notes of the chapter, it pops up. I've been assuming this had something to do with how much content can reasonably be displayed at one time, in a popup footnote. So that does explain it to my satisfaction.

Now the next thing: why are they even doing it this way? To me, if I click link 117, I want to see the note for 117--not 116, not 118, and certainly not a bunch of them together. Displaying them together when the reader didn't ask for them seems like an oversight to me, or an artifact of paper print days. But with an ebook, we should be able to link precisely and display precisely the target content of the link. Good support for this is how the other readers are handling it. And if they went ahead and changed this to display one note at a time, it would nearly eliminate this problem altogether (except in the niche case where you have one mondo footnote that has > 5000 chars in it--which does happen in some of my books).

The behavior I see tends to confirm that--the Kobo properly pops up the end notes toward the end of the chapter, even where the target has < 9 chars. I think the above item, the total char count of the note, seems to be the issue.

Yep. I suppose for Kobo, that gets even more tricky if the one destination note is a mondo note with > 5000 chars--then there'd still have to be some kind of solution for return navigation.

Of course, I can think of a better way to implement the case where there's too much footnote info to display in one popup screen, and *some* of my reader software does this: just provide a scrollable popup screen.