I have found part of the issue. The ABC file had some formatting commands at the very top. Once I removed those and saved the file again, the import of the melody improved.

However, BIAB is still not recognizing that when an accidental occurs in a measure, it remains in effect through out the rest of the measure unless another accidental happens. BIAB is not recognizing that the F natural in measure 1A is still in effect when it reaches the final F in the measure, and the only way to get back to an F# is to note it as such. Instead, BIAB is interpreting this as an F## (or G). See the picture below for the notation window after I removed the formatting commands from the ABC file. [img]https://www.dropbox.com/s/palr0vvej83e9fv/BIAB%202.jpg?dl=0[/img]