Where is the Tag and Filters Editor in 4.0?

Tag and Filters Editor has moved to the Publisher Bar

The Tag and Filters Editor that was previously on the left side of version 3.x has been moved to the Publisher Bar inside the Channel.

Enter the Channel, hover your mouse over the Publisher Bar  (directly below the Search Bar), and you'll see the Tags and Filters button Tags and Filters Button towards the right side.

Publisher Bar (2)

To see the Publisher Bar, you must have edit permissions for the Channel.