After directory rename, Frescobaldi doesn't show PDF

[David F.]

macOS 10.14.6
Frescobaldi 3.1.2

I was working on a song in Frescobaldi.  After renaming the directory that the 
song is in Frescobaldi no longer shows the PDF for the song after engraving.

Does Frescobaldi keep track of what PDF file belongs to what input file?  Can 
that information be flushed?

I’ve tried to reproduce the problem intentionally, but haven’t had any luck.  
Any help would be appreciated.

(Also, I’m posting this to the Lilypond list because none of my message go 
through on the Frescobaldi list.)

David