@Vincent_Vincent: Within the footer, just above the bottom margin or just below it, pushing the bottom margin upward ?
I don’t think any of those descriptions really fit how it works in the illustration, as they operate in the main text frame.
@nightflameauto: I have my suspicions that part of the problem lies in the length of my first footnote on the page that was having problems.
That could be an ingredient, yes. I’ve just run a quick test, and if a footnote is actually larger than a page, it does not properly balance it between multiple pages and loses it entirely. I don’t think that aspect of footnote layout is working at all.