XamDataGrid Custom ExpandableFieldRecordPresenter Style


I'm using the XamDatagrid Custom ExpandableFieldRecordPresenter Style example provided in the Infragistics WPF Samples Browser 2016.1.

My issue is that I have a horizontal scroll bar because the table possess many columns. When I scroll, the Expandable Field Record Header is getting scrolled out of the way. I want it to stay in place.

I tried switching this header to horizontal, but the same thing happened. The text is just getting scrolled out as I scroll to the right.

Now I assume there must be a way of doing it because if I don't change the style the text in the Expandable Field Record Header is following the horizontal scroll bar.

Thank you