The colouring in the image that Bernard linked to shows an interesting feature - for the male bird, the head and back are clearly blue rather than grey. And although the illustrations in my reference material show grey (to my eyes) the descriptions generally include: "blue-grey head and mantle" for the male Rock Thrush aka Rufous-tailed Rock Thrush.
The grey of Ivo's strange bird could have been intended as a "blue-grey". Descriptions also state, "... with white back ..." which, in video images I have (from Birds of the Western Paleartic - interactive
version) shows as a white patch when seen from a back virew or as a white "double-stripe" when seen in profile view. And that white-in-profile is very much like the white in the queried bird.
Apart from some apparent distortions in the sizes of various parts, the overall appearance including a relatively short tail does make sense for a Rock Thrush.
What does not make sense for me is the colour of the upper parts of the head! And yes, the eye should be mainly black, not mostly white. And the bill seems to be very pale instead of dark. And parts of the wing colouring don't tie up too well either. But these are just mere details.