Sadly, I can't even think of Shaw's vocalists right now from the 1938-1945 period outside of Helen Forrest...Tony Pastor? And there were a couple of others, I think...Billie Holiday too, of course, for 1938, but she's documented only on "Any Old Time".
I'd guess the Ellington set will have Ivie. (Hope they do, esp. since those two Hep volumes are so hard to come by these days; in the meantime, I think there's quite a lot of Ivy on that great 4-CD DKE 1930s import.) Al came later, in the 1940s.
Correct, the Ellington set will have Ivie.