Why is there a cut out on this generative fill backgroundimage?

[Raf350]

I removed the background of this image and kept the subject. I made a new background using generative fill and it looks great. However, when I turn off the subject layer, there is a cut out. Is there a way to resolve this? I would like to use this background for other pictures.

[Raf350]

For clarification, when I save the image as you normally would, the cut out seems to be imprinted to the image so that is what I wanna resolve.

[LAMY2017]

I've watched many Youtube videos by great instructors; they always seem to gloss over this issue, and seemingly skip a step.

What I do in this situation (others will have a more elegant method) is use the Lasso tool, surround the ghosts loosely, command-delete (Mac), then use one of the fills under the Edit menu --  Content-Aware or Generative.