I just upgraded to Finale 27. I tried changing my default font from "Jazz" to the new "Finale Jazz" that comes with v27 and the clef symbols all change to generic ampersands and Cs. If this font missing the clef signs?
The old Jazz was a licensed 3rd party font. I don't recall when it was announced that it would/could never be updated but that was many years ago (Finale 2012, maybe?). I remember discussions about it in the old forum that was deactivated five years ago.
There are a few workarounds but Peter's is the most efficient that I know.