Xamarin Forms StackLayout with two Frames not filling up the screen - xamarin.forms

Question

I see a very strange behavior that I can't understand. I am putting two Frames inside vertically oriented StackLayout. The first Frames' Vertical Option is set to StartAndExpand which renders correctly but the Second Frames' VerticalOption is set to FillAndExpand and for some strange reason it does not follow after the first Frame but from the middle of the screen. I want the Second Frame to immediately follow after the first Frame and take up the whole screen.
Code Below:
<RelativeLayout
x:Name="mainLayout"
HorizontalOptions="FillAndExpand"
VerticalOptions="FillAndExpand"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width}"
RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=1}">
<StackLayout
Padding="5,5,5,5"
BackgroundColor="Transparent"
HorizontalOptions="FillAndExpand"
Orientation="Vertical"
Spacing="0"
VerticalOptions="FillAndExpand"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width}"
RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=0.88}" >
<Frame
OutlineColor="Silver"
BackgroundColor="#FFFFFF"
VerticalOptions="StartAndExpand"
HasShadow="False" >
<StackLayout
BackgroundColor="Transparent">
<RelativeLayout
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=1}"
HorizontalOptions="FillAndExpand">
<Label
x:Name="To_Label"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.2}"
RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0}"
FontSize="Micro"
TranslationY="7"
FontAttributes="Bold"
HorizontalOptions="FillAndExpand"
VerticalOptions="CenterAndExpand"
TextColor="#2A84D3"
Text="To:">
</Label>
<Controls:DoneEntry x:Name="To_Entry"
Text="{Binding Model.To}"
RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.22}"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.70}"
VerticalOptions="CenterAndExpand"
HorizontalOptions="FillAndExpand" >
<CorcavBehaviors:Interaction.Behaviors>
<CorcavBehaviors:BehaviorCollection>
<PounceBehaviors:EntryTextChanged Command="{Binding ReceipientTextChangeCommand}"/>
</CorcavBehaviors:BehaviorCollection>
</CorcavBehaviors:Interaction.Behaviors>
</Controls:DoneEntry>
</RelativeLayout>
</StackLayout>
</Frame>
<Frame
OutlineColor="Silver"
BackgroundColor="#FFFFFF"
VerticalOptions="FillAndExpand"
HasShadow="False" >
<StackLayout
HorizontalOptions="FillAndExpand"
VerticalOptions="FillAndExpand"
BackgroundColor="Transparent">
<Editor
Text="{Binding EmailContent}"
FontSize="Micro"
HorizontalOptions="FillAndExpand"
VerticalOptions="FillAndExpand"
>
<CorcavBehaviors:Interaction.Behaviors>
<CorcavBehaviors:BehaviorCollection>
<PounceBehaviors:EditorTextChanged Command="{Binding MessageTextChangedCommand}"/>
</CorcavBehaviors:BehaviorCollection>
</CorcavBehaviors:Interaction.Behaviors>
</Editor>
</StackLayout>
</Frame>
</StackLayout>
<RelativeLayout
Padding="5,5,5,5"
RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=.12}"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=1}"
RelativeLayout.YConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=0.88}"
HorizontalOptions="CenterAndExpand"
VerticalOptions="CenterAndExpand">
<BoxView Color="#3E95D1" RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=1}" HeightRequest="1" />
<Controls:SwipeRightButton x:Name="SendEmail_Button"
BackgroundColor="#2A84D3"
OutlineColor="Silver"
HasShadow="False"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=1}"
RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=0.90}" >
<StackLayout x:Name="ImageLabelContainer"
RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Factor=1}"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width, Factor=0.90}"
Orientation="Horizontal"
HorizontalOptions="CenterAndExpand">
<Image
x:Name="connect_icon"
Source="sendemailwhite"
Aspect="AspectFill"
BackgroundColor="Transparent"
VerticalOptions="Center"
HorizontalOptions="Center">
</Image>
<Label
VerticalOptions="Center"
HorizontalOptions="Center"
FontSize="Micro"
TextColor="#FFFFFF"
Text="Swipe to Send" />
</StackLayout>
</Controls:SwipeRightButton>
</RelativeLayout>
</RelativeLayout>

Answer 1

Found the problem. The first Frames' VerticalOption should be Start instead of StartAndExpand.