So I am adding a leaf to the waterfall image. The leaf is on it's own layer with a layer mask, and was moved into position without a problem. A drop shadow was added with Layer Styles, but when trying to move the layer again, the mask moved, but the layer stayed behind.
I checked for Auto select, which was off. I unlinked the mask, tested, relinked the mask, and tested again. Same problem. Eventually it started working OK after I tried moving with first the layer active, and then the mask active, and swapping this state about three times. I could not get it to misbehave again after this.
Nothing was locked. Auto select was off. Other layers all moved OK. I can find no explanation, and think of no user error (touch wood).
Sorry for offtopic, but can you observe the bug when turning on the "Show transform controls" box in "move tool" and then begining only move (not transform) the layer (or mask) and the layer boundary left the artefacts on screen?