I create posters for boxing events. Usually these posters involve a background image with multiple pictures of fighters in the foreground. In the past, it has been easy for me to add a picture of a fighter and then remove the fighter from the background using "select and mask". This makes fighters look like he/she is on background. Then in the layer mask of the fighter I add a gradient from the bottom to top of the fighter image to blend them in. However, this Spring I had to re-install Photoshop on my computer and ever since, the gradient tool has not been working like before. Now when I apply the same steps as above, the gradient tool always pulls in the old background of the original fighter image - like I never did "select and mask" in the first place. I have no idea why this is now occurring and can't get the old functionality back. Please help!
If you want to apply multiple layer masks to one layer then you can group that layer and add a layer mask to the group folder.
You can apply a gradient to a layer mask without replacing it if the gradient goes from 100% to 0% opacity. I would suggest creating a separate layer mask for the group since this would be non-destructive.