Been using Photoshop since Version 2! I'm used to using the brush tool and QuickMask to create an alpha channel and use it as a layer mask. So having just upgraded to PS 2020 I'm attempting to mask an image. Sometimes I'm getting usge white pixels (like 30% of the image size). So I've experimented with the auto-masking tool and I can see it has generated a reasonably-accurate mask. I can see the mask layer and I can see the alpah channel. But it doesn't appear to have any effect on the image. The background is still there. Untile I create a layer behind my masked layer. Only then I can see the mask working. What gives?