The fix will be available in the R1 2018 SP2 Release.
When using the Office2016Touch theme and the default control template, the following binding errors can be observed in Visual Studio output:
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ContentPresenter', AncestorLevel='1''. BindingExpression:Path=(TextElement.Foreground); DataItem=null; target element is 'TextBlock' (Name=''); target property is 'Foreground' (type 'Brush')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ContentPresenter', AncestorLevel='1''. BindingExpression:Path=(TextElement.Foreground); DataItem=null; target element is 'TextBlock' (Name=''); target property is 'Foreground' (type 'Brush')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ContentPresenter', AncestorLevel='1''. BindingExpression:Path=(TextElement.Foreground); DataItem=null; target element is 'TextBlock' (Name=''); target property is 'Foreground' (type 'Brush')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ContentPresenter', AncestorLevel='1''. BindingExpression:Path=(TextElement.Foreground); DataItem=null; target element is 'TextBlock' (Name=''); target property is 'Foreground' (type 'Brush')
Setup
For your convenience, a reproducible project is attached.