Issue with LUT sampling in shader / ImageShader

[kkx64]

I'm trying to apply a 1024x1024 LUT (16x16 tiles, each tile 64x64) to an image with Skia, I converted the previous GLSL to work with Skia but I am only getting a whole cyan fill image at the end, and I'm completely lost as to what to do. The textures are loaded properly, since I can fade between the texture of the LUT and the image, and they are obviously loaded.

Shader:

  uniform shader lut;      // LUT texture
  uniform shader t;        // Input texture
  uniform float intensity; // Mix intensity

  vec4 applyLUT(vec4 src_color) {
    const vec2 tiles = vec2(16.0);
    const float tileSize = 64.0;
    
    float b = clamp(src_color.b * 255.0, 0.0, 255.0);
    float b_i = floor(b);
    
    vec2 tileIndex;
    tileIndex.y = floor(b_i / 16.0);
    tileIndex.x = mod(b_i, 16.0);
    
    vec2 pixelPos = src_color.rg * (tileSize - 1.0) + 0.5;
    vec2 uv1 = (tileIndex * tileSize + pixelPos) / 1024.0;

    return lut.eval(uv1);
  }

  vec4 main(vec2 pos) {
    vec4 color = t.eval(pos);
    vec4 lutColor = applyLUT(color);
    return mix(color, lutColor, intensity);
  }

How I load it:

<Shader
                    source={Skia.RuntimeEffect.Make(lutShader)!}
                    uniforms={{
                      intensity: filterIntensity,
                    }}
                  >
                    <ImageShader
                      fit="none"
                      image={lutTexture}
                      x={0}
                      y={0}
                      width={1024}
                      height={1024}
                    />
                    <ImageShader
                      fit="contain"
                      image={mainImage}
                      rect={{
                        x: 0,
                        y: 0,
                        width: imageDimensions.width,
                        height: imageDimensions.height,
                      }}
                    />
                  </Shader>

Example LUT: