Unfortunately, ID's footnoting has never been great, and several years ago its importing took a turn for the worse, losing notes for no obvious reason. One possible cause is detritus leftover from bibliography programs, but in my work that usually is not a factor. I used to think my use of Chinese characters (necessarily double-byte) caused footnotes to disappear, but now I'm inclined to think a series of revisions in MSWord is enough to through ID off.
Thanks for the quick response David.
When following your link to another thread, I read Pipilota Viktorina's suggestion to save "doc." files to "docx." and that seems to have worked! (so far).