I’m afraid that we would have to file this under “we would really love to make this work, but we can’t because of 3ds Max”.
When the color picker dialog is launched, it receives the original color only as its 8-bit (0-255) representation in the linear color space, which is then converted internally to the sRGB in the Corona dialog. Since this mapping is non-linear, sRGB values below 15 are mapped to the linear value 0 and there is no way to reconstruct the original sRGB values from the limited information provided by Max.