When you use the container option when using a scrolling container, images are tested against the window width to determine whether they are in the viewport instead of against the container's dimensions.
In my case, I have a scrolling container that only fills up 2/3 of the screen, so there are a few images that aren't visible that still get lazy-loaded. Ideally they would only load as you scroll the container.
Thanks for this well-done lazy-loader!
Fixed in 1.8.0
Better late than never ;)