The issue is a regression introduced with another fix, released in R2 2018.
When a new document is created and GetStatisticsInfo is called on it, a NullReferenceException is thrown.
When a separate file for setting the xaml styles is used and then this file is merged in App.xaml the style cannot be found. As a workaround merge the resources directly in the App.xaml. Fix available in LIB Version 2018.3.1029.