Wikipedia says this about Shadows:
"Cassavetes shot the film twice, once in 1957 and again in 1959. The second version is the one Cassavetes favored. Although he did screen the first version, he lost track of the print, and for decades it was believed to have been lost or destroyed. The 1957 version was intended to have the jazz music of Charles Mingus on the soundtrack, but Mingus failed to meet various deadlines set by Cassavetes. The contributions of saxophonist Shafi Hadi, the saxophonist for Mingus's group, proved to ultimately be the soundtrack for the film."
I don't think this is true. I think the music was for the 2nd version. Gary Giddens wrote this about it for the Criterion release (as part of a long essay on the film).
"Cassavetes signed the incomparable Charles Mingus, who insisted on written arrangements. The irony of a world-class improviser notating the score for a film otherwise afloat in improvisation may have been lost on Cassavetes, who tired of Mingus’s delays. In the end, the director settled for a few minutes of Mingus’s solo bass and several more minutes of Mingus’s alto saxophonist, Shafi Hadi. Mingus never completed a single arrangement for the film, but his sketches were later extended into such jazz classics as “Nostalgia in Times Square,” “Diane” (or “Alice’s Wonderland”), and “Strollin’.”"