This is correct, 4.5.0 was released at a later date than beta6 and thus some features in 4.5.0 are not in beta6 yet. In fact some of them still have not been merged to the 5 line as it requires quite some changes to the implementation.
If you want to test your application in 5 now, I would suggest using an older version of your model made in 4.4.4