After updating to ES App version 5.3.1, the extreme search commands no longer exist.
An error message is shown that the command is not found.
e.g.
Search: Access - Authentication Failures By Source - Context Gen
Unknown search command 'xsupdateddcontext'.
The Splunk Machine Learning Toolkit (MLTK) replaced Extreme Search:
https://docs.splunk.com/Documentation/ES/6.1.1/Admin/MLTKoverview
Extreme Search is not replaced until ES 6.0.