Why don't you use CustomListView?
In your project, changing the ContentHeight property in the Designer changes the visible part on the device !?
If I understand correctly then you are seeing the inner panel (the grey panel). I don't see a problem here.
You shouldn't use AutoScaleAll for the second layout.
What happens here is that there is a circular dependency between Panel1.Height which affects ScrollView.ContentHeight which then affects Panel1.Height again.
The value of Panel1.Height is not accurate in Page_Resize event as it was not yet resized.
The ContentHeight is not auto scaled. So it doesn't work automatically.