How to setup Qt theme?

[heitorPB]

I'm trying to configure Qt theme using catppuccin.nix, but I couldn't get it to work.

This is what I have:

{ ... }:
let
  catppuccinFlavor = "macchiato";
  catppuccinAccent = "blue";
in
{
  qt.style.catppuccin = {
    enable = true;
    apply = true;
    accent = catppuccinAccent;
    flavor = catppuccinFlavor;
  };
}

But when I try to open a Qt app I get plain white unthemed app. I also get a weird messaged about missing Kvantum:

$ pcmanfm-qt
QApplication: invalid style override 'kvantum' passed, ignoring it.
        Available styles: Windows, Fusion

Apparently qt.style.catppuccin is not enough to the get the theme. What I am missing?

[Anomalocaridid]

Do you have qt.style.name and qt.platformTheme.name both set to "kvantum"?

If so, have you tried logging out and logging back in again?