Lost Substitution Variables tab in Sept release

Summary:

Since the September release went in to our Test environment we have lost the sub tab for Substitution Variables.

Content (please ensure you mask any confidential information):

When we click Variables menu we only see User Variables. The tabbed menu along the bottom is not showing, so can't see the Substitution Variables tab.

Version (include the version you are using, if applicable):

26.09.58

Code Snippet (add any code snippets that support your topic, if applicable):