It think this is covered in "the bible" - Unstructured FM8 (now updated for FM11) put out by Scriptorium - cheap PDF copies are for sale from them of the FM8 book, but I think we're still waiting for PDFs of the FM11 one to be made available. You can also check the Scriptorium wiki which is based on the FM8 book.
I just figured that out. The maximum height was set too low. I was trying to use the paragraph styles to keep the footnote with the previous one, but that was not working.
My problem is fixed for the time being.
But, I would still like to know if anyone knows if there is a way to automatically ensure that footnotes appear either on the left page or accompanying right page, even if doing that adds white space.
> ... automatically ensure that footnotes ...
If you want automatic, you're pretty much limited to what FM provides, and FM's footnote functionality hasn't been enhanced to any great degree in the last decade or so.
The feature most commonly requested is endnotes.
Adobe telegraphed the answer "fuggedaboutit" when they documented how to simulate those by using the long-standing Xref hack. Footnote text at end of flow in numbered paragraphs. References earlier in body are superscripted Xrefs by paranum.
to numbered paras in text frames,
inside anchored frames,
anchored to bottom-of-column,
you can make what appear to be footnotes do more or less what you want, but it is some distance removed from being "automatic".
> Why would that xref process be better than an endnote marker,
> which allows auto creation of the endnotes via an index of markers.
> No need for the xref process described...
Unless you are describing something new with FM10 or 11, I'm guessing that the endnote display text would be the Marker Text.
The one time I looked at doing a project that way, the elemental plaintext nature of the marker text quickly became a problem (no Xrefs in that text, no URLs in that text, no character formatting, etc.).