Hoping this is not too much of a derailment, but as long as we're talking pre-'48 Paramount movies, I'll ask this question here:
I caught part of a movie on a TV station years ago that had the pre-48 Paramount package, and maybe some pre-48 WB's and RKO's too, but I'm very certain it was a Paramount movie. There was a musical number where one woman was singing in a nightclub while another did a ballet dance nearby, flanked by chorus girls in sour-faced masks. Eventually, the masked girls surround the main dancer, and when they disperse, she is on the floor wearing an identical mask to them. I've been googling all manner of permutations of B&W movie, masked dancers, etc, to no avail; there were suggestsions of DAMES and SHALL WE DANCE, but I know it's not them, and when I posed this to someone else, they suggested LADY IN THE DARK, but that's a color film.
Any hunches?