When adding a ListView inside a ScrollView, and when that ListView has transitions define, it can happen that while adding and removing elements from the model, some of the items are not immediately visible whereas they should remain visible.

Run the attached example. Click on Header 2, scroll to the bottom, click on Header 3. Header 3 is not visible on the display, and only becomes visible when scrolling or resizing the window.

Removing the transitions hides the issue. Removing the ScrollView as well. It mostly comes from the connections made from flickableItem.contentY to scroller.verticalScrollBar.value in ScrollView. Evidence also points to the inverse binding in ScrollViewHelper.