When stairs are moved in any direction, in any orientation, with pistons, their texture will be changed to the purple and black "no texture" texture whilst moving, and then revert to the correct texture.
I tried to take screen shots of the phenomenon, but the delay between screenshot and piston movement mean that it could not be done.
This is probably also related to MC-57209, which was published whilst I was writing my report. Otherwise, I have found no duplicate issues.