Use of generative fill

It would be helpful to see the image you are trying to edit.

Is this person in a group with other people? 

Are they alone in an open space?

How tightly, or loosely is the selection you are making of the person you want to remove?

With the selection below, Generative Fill did a good job.

But the Remove Tool did an equally good job.  

In a groups situation like below, a fairly tight selection did an OK job with the man in the background, but Generative Fill would not be able to give a good result if you asked it to remove one of the two ladies in the fron row.

This is what happened when I tried, and it looks rather like what you described