HI,

 I am attaching a new sample. I changed the path to NestedContent and added a converter.
 In the converter you can get access to the child object.

 I replicated your issue when clicking on the 2nd button. The XamDataGrid scrolls up.

 I will create a private case for this issue and email you the details.

 Sincerely,
 Matt
 Developer Support Engineer

That's better but when you uncomment field settings, run the program and expand both rows then click second button then first row disappears (a bug I suppose ? I'm currently using v12.1).
It seems to scroll up outside visible area (but no scroll bar is shown) - pressing Page-Up brings it back.

Another thing: assuming my binding path is "Child", how can I access this child object and its properties in ExpandableFieldRecordPresenter ? Based on documentation of ExpandableFieldRecord  I've tried:

{Binding RelativeSource={RelativeSource TemplatedParent}, Path=NestedContent.Value}

But it evaluates to object of type CVPValueWrapper. It seems that CellValuePresenter.Value.get() is completely broken - it does not return dependency property value but a computed value - that works in code behind but not in bindings and is an absolutely wrong way of implementing DependencyProperty wrappers :(