The new expandable area widget in 4.11 can not be copy pasted properly.
When you have content in the header and the body and then try to copy past it, its content is copied outside of the body and header.
Have a great day and keep the great work flowing 
Hello bigzer,
I was able to reproduce this issue on our end. I have written up a report (UE-29987) and I have submitted it to the developers for further consideration. I will provide updates with any pertinent information as it becomes available. Thank you for your time and information.
Make it a great day