Only occurs on UWP target, found when updated to latest version (from 18.104.22.168 which works fine).
Setting PrimaryAxis.TrackballLabelStyle.AxisLabelAlignment throws a NullReferenceException.
To test I created a plain Xamarin Forms app in VS 2017. Added a single SfChart control to the main window.
<syncFusion:SfChart x:Name="Chart" HeightRequest="200" WidthRequest="400" />
In the code-behind constructor:
Chart.PrimaryAxis = new DateTimeAxis();
Chart.PrimaryAxis.TrackballLabelStyle.AxisLabelAlignment = ChartLabelAlignment.Near;
Will throw exception when constructor returns, I assume when the control is rendered. Callstack attached.
Actual code sets this property sometime later and this still throws the same exception.