OK great thanks for the assistance. Much appreciated.
After much googling, I managed to track this down to a reported issue on github. It seems its related to the new project structure which means items in the Core project are not accessible from Application.Shared.
https://github.com/aspnetboilerplate/aspnetboilerplate/issues/4620
I hope it helps someone and saves them some searching to track down the issue.
Regards, Barry.
