I work on a number of InDesign files that are updated every year. Several of them give a message when printing that says "The following fonts are not currently available:" and it names an old version of a font that we use. That version of the font doesn't show up in Find Font, and as far as I can tell it isn't specified in any paragraph or character style. Any ideas why this might occur?
We currently use ID 5.5, but this has happened for years, going back several versions.
Try exporting the file to .idml.
You can also use find/chnage to see if it can locate the font (but it seems unlikely it's on a page if Find Font doesn't see it). Are you sure it isn't in some linked file?
I had a similar experience but exporting to ePub. I was getting the message that a font was missing, but it wouldn't tell me where. Find/font didn't show anything. The only way I spotted it was searching for it in the CSS file. It was in a paragraph style I was using for captions. But in the captions I was using a different font, probably as an override. But the original font reported by the ePub export was in that paragraph style. Just double check again the fonts in your paragraph styles.