UWP AdaptiveTrigger Not Triggering - xaml

Question

I have the VisualStateManager inside the root grid, but it's not triggering the AdaptiveTrigger. I'm trying to change the textblock inside the StackPanel. Also, what are the rules on priority of VisualState setters over the default? For example, the textblock CreateNewAccount is using x:Uid to get a string resource, but when the setter tries to change the Text value, which one gets priority? Same with FontSize being set by a static resource style.
<Page.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="../Style/ApparentTheme.xaml"/>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Page.Resources>
<Grid x:Name="MainGrid" Background="{ThemeResource ApplicationPageBackgroundThemeBrush}" Margin="20 0 20 0">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup>
<VisualState x:Name="Mobile_720">
<VisualState.StateTriggers>
<AdaptiveTrigger MinWindowWidth="720" />
</VisualState.StateTriggers>
<VisualState.Setters>
<Setter Target="CreateNewAccount.FontSize" Value="12"/>
<Setter Target="CreateNewAccount.Text" Value="Test"/>
</VisualState.Setters>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="2*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<StackPanel x:Name="FormStackPanel" Grid.Row="0" Grid.Column="1" Orientation="Vertical">
<TextBlock x:Name="CreateNewAccount" x:Uid="CreateNewAccount" Style="{StaticResource TitleTextBlockStyle1366}"/>
<TextBox x:Uid="EmailField" x:Name="emailField"
Style="{StaticResource TextBoxStyle1366}" InputScope="EmailNameOrAddress"
Text="{Binding NewSignUp.Email, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<TextBox x:Uid="FirstNameField" x:Name="firstNameField"
Style="{StaticResource TextBoxStyle1366}" InputScope="AlphanumericFullWidth"
Text="{Binding NewSignUp.FirstName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<TextBox x:Uid="LastNameField" x:Name="lastNameField"
Style="{StaticResource TextBoxStyle1366}" InputScope="AlphanumericFullWidth"
Text="{Binding NewSignUp.LastName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<PasswordBox x:Uid="PasswordField" x:Name="passwordField"
Style="{StaticResource PasswordBoxStyle1366}"
Password="{Binding NewSignUp.Password, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<PasswordBox x:Uid="PasswordConfirmField" x:Name="passwordConfirmField"
Style="{StaticResource PasswordBoxStyle1366}"
Password="{Binding NewSignUp.PasswordConfirm, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<Button x:Uid="CreateAccountButton"
Style="{StaticResource ButtonStyle1366}"
Command="{Binding CreateAccountCommand}" Click="CreateAccountButton_Click"/>
<TextBlock x:Name="errorMessage"
FontSize="16pt" Foreground="Red" Margin="0 5 0 0"
Text="{Binding SignUpErrorMessage, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}"/>
<ProgressRing x:Name="signUpProgressRing"
HorizontalAlignment="Center" IsActive="False" Height="30" Width="30"/>
</StackPanel>
</Grid>

Answer 1

It is better to design for a small form factor, and use AdaptiveTrigger for larger widths and heights. Because I was doing the opposite, and testing on a smaller mobile screen, I was unable to see the changes. Here is the revised XAML:
<Page
x:Class="apparent_uwp.View.SignUpPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:apparent_uwp.View"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Page.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="../Style/ApparentTheme.xaml"/>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Page.Resources>
<Grid x:Name="MainGrid" Background="{ThemeResource ApplicationPageBackgroundThemeBrush}" Margin="20 0 20 0">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup>
<VisualState x:Name="Mobile_720">
<VisualState.StateTriggers>
<AdaptiveTrigger MinWindowWidth="720" />
</VisualState.StateTriggers>
<VisualState.Setters>
<Setter Target="CreateNewAccount.FontSize" Value="24"/>
<Setter Target="MainGrid.ColumnDefinitions[0].Width" Value="*"/>
<Setter Target="MainGrid.ColumnDefinitions[2].Width" Value="*"/>
</VisualState.Setters>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<StackPanel x:Name="FormStackPanel" Grid.Row="0" Grid.Column="1" Orientation="Vertical" Margin="10 0 10 0">
<TextBlock x:Name="CreateNewAccount" x:Uid="CreateNewAccount" Style="{StaticResource TitleTextBlockStyle}"/>
<TextBox x:Uid="EmailField" x:Name="emailField"
Style="{StaticResource TextBoxStyle}" InputScope="EmailNameOrAddress"
Text="{Binding NewSignUp.Email, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<TextBox x:Uid="FirstNameField" x:Name="firstNameField"
Style="{StaticResource TextBoxStyle}" InputScope="AlphanumericFullWidth"
Text="{Binding NewSignUp.FirstName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<TextBox x:Uid="LastNameField" x:Name="lastNameField"
Style="{StaticResource TextBoxStyle}" InputScope="AlphanumericFullWidth"
Text="{Binding NewSignUp.LastName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<PasswordBox x:Uid="PasswordField" x:Name="passwordField"
Style="{StaticResource PasswordBoxStyle}"
Password="{Binding NewSignUp.Password, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<PasswordBox x:Uid="PasswordConfirmField" x:Name="passwordConfirmField"
Style="{StaticResource PasswordBoxStyle}"
Password="{Binding NewSignUp.PasswordConfirm, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<Button x:Uid="CreateAccountButton"
Style="{StaticResource ButtonStyle}"
Command="{Binding CreateAccountCommand}" Click="CreateAccountButton_Click"/>
<TextBlock x:Name="errorMessage"
FontSize="16pt" Foreground="Red" Margin="0 5 0 0"
Text="{Binding SignUpErrorMessage, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}"/>
<ProgressRing x:Name="signUpProgressRing"
HorizontalAlignment="Center" IsActive="False" Height="30" Width="30"/>
</StackPanel>
</Grid>