ListPicker does not “push down” other elements

ScrollView
StackLayout VerticalOptions="Start"
local:myListPicker x:Name="LP" /local:myListPicker
Label Text="Push me" /Label
Label Text="DOWN" /Label
/StackLayout
/ScrollView

I added four Items to the ListPicker, when I tap on it, it opens, but only the first one can be seen, since it does not "push away" the two labels under it.

It looks like the ListPicker is "behind" the two labels, why is that and how to fix?

Additinol Info:
- ExpansionMode equals ExpansionMode.ExpansionAllowed.
- With 5 or more Items in the List it gets fullscreen (which is totally OK)