New page load shows contained banner image, then stretches to fill whole page
I have page banners at the top of all my pages. I use a container and it doesn't matter if the Content Width has Full Width or Boxed selected. I also set 'Stretch Section' to YES.
When I load a paged, the banner should automatically load with the banner fully stretched across the whole page, but this does not happen. When I load a page, the banner image is shown in a Boxed container, and then stretches to the full width across. This shouldn't be happening. All my other websites do no do this.
I have uploaded a video to my webhost so you can watch and see what I mean. It's only 12 seconds long.
See the problem: https://eagleworldwidenetwork.com/video/delay-stretch.mp4