The behavior of the Graphics object for the D2D and OpenGL renderers is that the image is not completely written/flushed intil the Graphics object goes out of scope. The example you provided should work if you add a scope around the Graphics object. If that’s still broken, please let us know.
juce::Image result (juce::Image::ARGB, 9, 9, true);
{
juce::Graphics g (result);
g.fillAll (juce::Colours::white);
}
jassert (result.getPixelAt (2, 2).toDisplayString (true) == "FFFFFFFF");
This has come up at least once in the past, so we should probably update the docs to make this a bit clearer.