I couldn't figure it out either. 
I think it sometimes has something to do with the placement of the id tag in the referenced code, but not always.
causes "jump":
<p class="footnote"
id="note15"><a class="color" href="act01a.html#note_15">
causes sticky note:
<p class="footnote"><a class="color" href="act01a.html#note_15"
id="note15">
So you can edit the book and use a complicated regex replacement to change one to the other. Unfortunately this doesn't always work!!!
There is also two different behaviors (sticky note/jump) on the new Calibre 5 ebook reader on laptop/desktop, so maybe the Calibre developers know something about this.
If you figure anything out let me know.