Thank you for the response and the link. Also thank you for a comment you made a few posts up when you said “The background is behind the container”. That made me look and I realized in my child theme I’d given the container a white background color.
As a workaround I changed the body background-color to white and gave the content area an rgba color of rgba(255,255,255,0) instead. So the color is still white but due to the opacity, the parallax picture made with The Page Builder shows now.
So it works nicely now. The main problem though in both your implementation and Adam Rob’s implementation is that the parallax picture doesn’t scale down on the phone properly. It shows a cropped version of the picture so only some blurry pixellated image shows for the background on a phone. They do however scale down properly on the computer screen using Firebug.
The parallax effect still doesn’t work on the phone which is understandable but if the picture would scale, then at least you could have a still picture on the background and it would still look good.
By the way, There’s a free WordPress theme called Aladdin that comes with a parallax background for the front page. The first parallax section works well on my Android phone and the parallax effect is present. Perhaps by examining it you might figure out a way to get yours working too.
Thanks you again for all your help and support.