After the update to version 17.0 last week, I have opened several publications that were in progress. None of them have any type 1 fonts in them as the blue pop-up has been around for awhile. But now these pubs show the error. However my preflight window shows no errors, and clicking on the number in the blue banner to pull up the replace fonts dialogue also shows no type 1 fonts in the document.
I understand the only way to replace the annoying banner is to remove the offending fonts, but what if there are no fonts to replace? Is there no way to dismiss the banner?
I'd check your unused paragraph and character styles. As well as the "font" used for your default sytle and any funky settings for your story editor. If a Type 1 font is listed in one of your styles, you'll get the @*#%! blue banner every time, but it'll never show up when you Preflight the document. Because Preflight only checks the type styling you actually use in the document.
I know this because I've fought it myself. Hopefully I can save you some of the learning curve on this one.