Can't Reset Fretboard Fingering Labels

[Stringtheorist]

I don't know whether an old file of mine has become corrupted but the fretboard diagram in my document won't "forget" the displayed fingering for the A string when I delete the note, and shows a fingering even when there is no note on the string! Deleting the diagram and copying another from within the same document produces the same result, so I assume all the diagrams on the page exhibit this behaviour.