paramList.visibleArea.heightRatio is updated when scrolling down the list whereas the size of the listview does not change

Start the QML in attachment:

• watch the text label at the bottom left of the screen, the paramList.visibleArea.heightRatio equals 0.57 which is correct
• press the right arrow key and then press the left arrow key, the focus came back on the first item of the horizontal listview
• the paramList.visibleArea.heightRatio equals now 0.42 which is incorrect
• when scrolling down with the down arrow key, the paramList.visibleArea.heightRatio changes suddenly to the correct value 0.57

This issue does not occurs if I set a fixed value in the paramList.height listview.

If I write a custom property customHeightRatio which behaves correctly.