Weird lazy loading behavior when you have a lot of sources on element index page

[angrybrad]

Environment:

• Craft version: 3.x
• PHP version: 7.x
• Database driver & version: n/a
• Plugins & versions:

Description:

I ran into a situation where the ElementIndex doesn't fetch more elements when you have more sources (asset folders in this case) than elements per call. If you look at the attached image: you'll see that I've seen the latest asset, but I have to scroll all the way down to load more, because of all the folders I have on the left side.

[brandonkelly]

Guessing this was fixed via b012155