I had previously gotten the sense that EH resented the presence in the US of Brazilian folksinger/guitarist, Olga Coelho, but an article last year in Digestivo Cultural on Coelho provides some details (that don't speak terribly well of EH).
Here's the relevant paragraph:

Consagrada, de volta ao Brasil, Olga arranja mais viagens. Por indicação de Villa-Lobos e do escritor Erico Verissimo, é convidada pelo governo americano para se apresentar em Washington e Nova York. Em 1938, canta na Casa Branca para Eleanor Roosevelt e assina contrato com a RCA Victor. Ela e Gaspar se instalam num apartamento na Sétima Avenida, defronte ao Central Park. Seu concerto no Town Hall é um sucesso. A crítica solta rojões. Camargo Guarnieri a convoca para lançar árias suas, para inveja de Elsie Houston (1902-1943), soprano amiga de Mario de Andrade que, até a chegada de Olga, tinha monopólio do folclore verde-amarelo em Nova York. “Elsie falava mal de mim e brigava com todos. Era problemática. Casou-se com um barão belga, que a roubava. Terminou por se atirar do seu quarto de hotel em Manhattan, deixando o filho de 11 anos à janela e Camargo Guarnieri à espera dela na estação, pois iam fazer um recital em Washington.”

As you know, I don't know Portuguese [and would love a real translation], but here's what I get (note, it is from Coelho's point of view):
Elsie Houston was envious that Camargo Guarnieri was writing a piece for Coelho and that Coelho was disrupting her monopoly on Brazilian folk song in New York. So she spoke badly about Coelho to everyone. Another detail: Guarnieri, unaware of Houston's suicide the night before, was left waiting at the train station for her (they were scheduled to perform in Washington).

A compilation of old French 78s has shown up on various mp3 music sites. Elsie Houston is listed as singing "Tu m'as donné Paris." If you listen to the sample, though, you hear a voice very different than the Elsie Houston we know (lower register, belty). I suspect the compiler mixed up the credits. "Amour…Amour..," credited to "Yolanda" is much more EH-like. Any opinions?