my xaml is as follows:
The issue is when MyCollection has only one object in it, otherwise things are working well.
<chart:SfChart Margin="0,10,0,10" BackgroundColor="Transparent" >
<chart:SfChart.HeightRequest>
<OnIdiom x:TypeArguments="x:Double" Phone="350" Tablet="450" />
</chart:SfChart.HeightRequest>
<!--<chart:SfChart.Title>
<chart:ChartTitle Text="Chart Title" />
</chart:SfChart.Title>-->
<chart:SfChart.ChartBehaviors>
<chart:ChartZoomPanBehavior />
</chart:SfChart.ChartBehaviors>
<chart:SfChart.PrimaryAxis>
<chart:DateTimeAxis IntervalType="Days" LabelsIntersectAction="MultipleRows" ZoomFactor="1" PlotOffset="0" IsVisible="True" ShowMajorGridLines="False" EdgeLabelsDrawingMode="Center">
<chart:DateTimeAxis.Title>
<chart:ChartAxisTitle Text="Date"></chart:ChartAxisTitle>
</chart:DateTimeAxis.Title>
</chart:DateTimeAxis>
</chart:SfChart.PrimaryAxis>
<chart:SfChart.SecondaryAxis>
<chart:NumericalAxis Name="Values" PlotOffset="50"
Interval="25" Minimum="0" Maximum="100" ShowMajorGridLines="True">
<chart:NumericalAxis.Title>
<chart:ChartAxisTitle Text="Y values"></chart:ChartAxisTitle>
</chart:NumericalAxis.Title>
</chart:NumericalAxis>
</chart:SfChart.SecondaryAxis>
<chart:SfChart.Series>
<chart:RangeAreaSeries EnableTooltip="True" ItemsSource="{Binding MyCollection}" XBindingPath="Date"
Low="LowerValue" High="HigherValue" Color="#FF7F50" LegendIcon="Circle" >
<chart:RangeAreaSeries.TooltipTemplate>
<DataTemplate>
<Grid Margin="0,0,0,0" BackgroundColor="#EAEAEA" Padding="5,5,5,5">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Label Text="{Binding Date}" TextColor="#212121" Grid.Row="0"></Label>
<Label Text=": " Grid.Column="1" TextColor="#212121"></Label>
<Label Text="{Binding HigherValue}" TextColor="#212121" Margin="0,0,0,0" Grid.Row="0" Grid.Column="2"></Label>
</Grid>
</DataTemplate>
</chart:RangeAreaSeries.TooltipTemplate>
</chart:RangeAreaSeries>
</chart:SfChart.Series>
</chart:SfChart>