How to fix SQL Server Management Studio 2014 IntelliSense when intermittent
If possible, I'd suggest trying SSMS 2016 instead. 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). With 2016, SSMS is now free, and the installer for it is separate from the installer for the SQL Server server components (Database Engine, Integration Services, etc.). Plus, Microsoft is now releasing updates and improvements for it on a roughly monthly basis.

You can download SSMS 2016 from https://msdn.microsoft.com/en-us/library/mt238290.aspx.

I've personally found IntelliSense to work more reliably with SSMS 2016 than what I was used to with 2014, especially when working over slower or less reliable network connections.