When you put a sand block, the texture of it is rotated randomly, so that it looks less uniform when there are sand blocks together, however, when you put a sand block in a position where the block can fall, it calculates the rotation of the sand before falling, causing that when it transforms from entity (falling-block) to block, it rotates again. It should calculate the rotation before falling, and not rotate again when transforming.

EDIT: I wouldn't call it a parity issue, but in Bedrock Edition it works as I describe above.