When we listen to scroll events we currently only detect if a user scrolls the entire page, not if a user scrolls within a DIV or any other element. This means we cannot detect whether a content block becomes visible if is placed within a scrollable element which can be the case sometimes. We need to check all parent elements of a content block whether they have overflow: scroll and if so connect an event to this.

Note: We will not detect if a user adds this style after page has loaded. Only the ones at page load will be detected.

As it is not too hard to implement I reckon short term