The cache is refreshed asynchronously in another session.
It sounds like two separate intellisense behaviors are perhaps being discussed in the comments. The discussion is around refreshing the cache in the case of schema changes, but "not working" could also just mean the intellisense dialog intermittently doesn't appear at all when it should. It's still supported to use it against SQL Server 2014 (in fact, it's supported to use it against instances as old as SQL Server 2008).
Intelli Sense can be a very powerful ally for the T-SQL developer.
It can significantly reduce keystrokes, prevent you from guessing at object names, make sure you spell them correctly (and use the right case), and can help you understand the interface to several programmable entities such as stored procedures and built-in functions.
(SSMS doesn't display any progress indicator or any info related to loading process of Intelli Sense) Thank you for your interest in this question.
Note that most of these items are also applicable to previous versions.
There are a couple of different symptoms that can lead you to believe that Intelli Sense is "not working." One is where the Intelli Sense features (auto-complete / list members / tool-tips / underlining invalid references) do not function at all.
At first, everything seemed to be going great, until I noticed that Intelli Sense is intermittent. So by intermittent I mean that sometimes I see the list of tables, and sometimes I don't.
By "intermittent" I mean that on the same computer, while working on the same script, Intelli Sense might appear some times and not appear at other times. This just a specific example of how the symptom manifests. I mean that whenever I expect Intellisense to appear, it doesn't always appear.