The Rachmaninoff Question

Having worked my way to the end of my project to write a series of pieces on my Examiner.com national site about the recordings in Arturo Toscanini: The Complete RCA Collection, I discovered something interesting about which composers among his contemporaries he chose to record. I knew that Ottorino Respighi would be there, since the old vinyl of "Pines of Rome" and "Fountains of Rome" was one of my childhood favorites. I also knew that he had conducted the American premiere of the seventh ("Leningrad") symphony of Shostakovich. Still I was a bit surprised to discover that, among all of those CDs, while both Shostakovich and Sergei Prokofiev were represented, Sergei Rachmaninoff was completely ignored. This is somewhat curious since Rachmaninoff also recorded with RCA. This has led me to wonder: Could it be that Rachmaninoff so disliked Toscanini that he refused to let him have anything to do with any of his compositions?