The subtle tones in the sky are visible its just that compared to the amount of interest in the rest of the picture it leaves the top quarter looking empty. A square crop (only taking off the top) would bring it much more balance
Its a great scene and well captured, this is where landscape photography gets hard though, mother nature has to be willing to play the game too and if she doesn't, then there is simply no amount of camera skill that will get around that!!
Try a squarer crop Jack as it will balance up much better, especially as you have placed the rock in a nice diagonal to the sun and exposed the foreground well at the same time as the background
