Importing Footnotes

I'm trying to import RTF documents that have footnotes, but the footnotes are imported inconsistently. The numbers show up as they should, but most of the footnotes have blank content. The RTF files are pretty much run-of-the-mill; they do not have tables or fancy formatting. They have only text with footnotes and annotations (comments--they don't get imported). I can't see any distinguishing features between the footnotes that do get imported and those that don't.