Footnote Bug

Scrivener has begun doing something very frustrating. When I “block” a piece of text and Control/Shift/F to designate it as an inline footnote, about half of the time it just grays the text and puts the gray box designating the inline footnote about 10 lines further down the page in a random place - generally, but not always, in a space between paragraphs. Very frustrating! Any ideas why and what to do about it?