I am not sure if "export to root template" never worked or stopped working in the DE editor after the latest patch, but it also doesn't work for me.
At the moment your only option would be to "create new from selected", creating a new character directly from an other root template and edit that.
The engine always had the bad habbit of crashing when closing it. Just make sure you have saved yor work and click "force exit". The editor will then close without problems.
