1. Citrix Workspace Environment Management Documentation: In the "Transformer settings" article, under the "Advanced" tab description, the documentation for the "Log Off Web Portal When Session is Launched" feature explicitly states the prerequisite.
Source: Citrix Product Documentation, Workspace Environment Management, Current Release, Configuration, Transformer settings.
Reference: "To use this feature, you must also set the Workspace Control settings on the StoreFront store to Do not log off a session when users log off from StoreFront."
2. Citrix StoreFront Documentation: The Workspace Control settings are configured within the StoreFront console for a specific store. The relevant setting is the "Logoff action."
Source: Citrix Product Documentation, StoreFront, Current Release, Manage the delivery of resources in a store, Configure workspace control.
Reference: The "Logoff action" setting within Workspace Control determines whether user sessions are terminated, disconnected, or left running when they log off from a store. To meet the WEM prerequisite, this must not be set to "Terminate."