I believe something shady is going on with masks in latest beta. Look at screenshots. I have fully-white mask with black area carved in it, added to layer.
If you command-click on a mask (turning it into selection) you will get not the mask contours itself - but limited with the bounds of the parent layer! Which is definitely not needed/not useful.
And even if you release mask and make selection from it again - you still get some weird bounds (of the mask itself). In previous versions, mask selection was made from all the white area inside the mask - so mask selection was bounded with document size, not the layers inside it. Since mask is totally white, except black blob in it. such unrelated bounds just ruin mask selections //
* this bug is also present in [1.8.1.170]