"Error rewriting document" when adding Quick Controls item to Form Editor

Getting an error when trying to add Qt Quick Controls 2 item from Item library to Form Editor, see picture. 

Steps to test:

1. Create a project
2. Add QtQuick.Controls import
3. Try dragging and dropping Check Box from Item Library to the Form Editor -> Error dialog "Error rewriting document" opens and item is not added

Some of the Controls items can be added without error, e.g a Dial.