The question says it all I think.
When I paste into a layer mask, the pasted pixels re-orientate themselves into the centre of the image.
But I would like them to maintain the exact position they were in on the layer I copied them from.
Is this possible, and if so, how?
Use Paste-in-Place, Layer via Copy or Alt Drag
Copy in Place: Ctrl+Shift+V
Layer via Copy Ctrl+J
*Both do the same thing with layers.
Also, when copying one layer mask on to a new layer. Hold down Alt and drag to the new layer.