Note Plays As Incorrect Pitch

During sessions of editing/revising notes, I have encountered this issue more than once:
I end up with a note that plays as an incorrect pitch.
The attached score demonstrates the issue.
This score consists of just one measure with two notes.
Both notes appear as B on the treble clef.
When played, the first note sounds the correct pitch.
But the second note sounds an incorrect pitch F (6 semitones below).
The only workaround that I have found is to delete the offending note, then recreate it.
I don't know how to recreate the issue from scratch.