flickable contentY is set to 0 when change the size itself

Hello guys, I have a strange problem . I use a GridView and anchor.fill it to the ApplicationWindow . I set contentX and contentY of GridView to some values . When I resize the parent windows, the contentY is automatically set to 0 !!!!! , contentX is still OK . I don’t know it is a bug or I’m wrong at some points. Could you please help me ? Thank you!