SQL agent jobs hung state (SSIS jobs hung)
We noticed similar behavior few times within a year on one of the production server with SQL Server 2014 SP2 installed.

Symptom: All SQL Agent jobs that run SSIS packages suddenly hanged in running state, while no real activity on data engine side.

Resolution: Both times this issue was resolved by pushing all pending windows updated patches to be installed. After this SQL Agent was restarted and jobs behavior was normal again.

Seems the issue is somehow related to .NET stack on a server and OS that we obtain via WSUS