where exactly was Rita hayworth's oscar nom and films noms?

Back then the film was rather considered as a trashy melodrama.

But I think the real problem was that in 1947, when the Oscars for the films of 1946 were given, there were much less nominees in categories like Best Cinematography (b&w, color), Best Art Direction or Best Song, to name a few. In some categories there used to be 10 nominees and suddenly there were only 5 or 3!
And another disadvantage for "Gilda" was that the category Best Costume did not exist, yet.
It was similar or worse with the Golden Globes. And famous other awards or film festivals did not even exist, yet either.

In other words: the film had very bad timing. Still, Rita should have been nominated, at least! But Columbia was also not prestigious enough to have more impact on the Academy to get a nomination for their biggest star who was rather known as a "glamour girl" and not as a serious actress.

I just found out that "Gilda" was actually nominated for the Grand Prix (the Golden Palm did not exist, yet) at the very first film festival of Cannes!!! IMDb does not list it but in the archive of the festival (http://www.festival-cannes.fr/en/archives/1946/inCompetition.html) you can find it.

It was nominated along with Hitchcocks "Notorious", Cukors "Gaslight", Wilders "The Lost Weekend", Rossellinis "Roma citta aperta" and Cocteaus "La belle et la bête", to name a few.

Well, at least the French noticed the brilliance of the film back then!