I just tried the March 2.3 release of photoshop, and discovered that select subject and select mask are doing really bizzare things.
When you select subject all looks well, but when you go into select and Mask, the selection is missing, and the wrong layer is being shown, its alway the background layer. You can't edit the selection or do anything, if you try and re select the image you are told that you are going to get rid of the current selection, but then no selection is made. What is going on, I depend on this feature a lot.
When I went to duplicate the issue, all of a sudden it was working. Proior to this I restrted PS and then the Mac with same issue. This time I just started up PS same photo same everything and this time it worked. Now I am more mystified then ever. Thanks for having me go back and try again.