Explanation
Two possible causes why no people are entering a live journey with a system generated event are:
* A wrong URL is being used. A system generated event is an event that is created and sent by an external system or application to Adobe Experience Platform using an API call. The API call must use a specific URL that contains the sandbox name, dataset id, and schema id of the event schema that defines the structure and semantics of the event data. If a wrong URL is used, such as one that contains an incorrect or missing sandbox name, dataset id, or schema id, the API call will fail and the event will not be created or sent to Adobe Experience Platform and Adobe Journey Optimizer.
* The event payload does not contain an event id. An event id is a property that uniquely identifies an event within Adobe Experience Platform and Adobe Journey Optimizer. An event id is required for an event to be processed and ingested by Adobe Experience Platform and to trigger a journey in Adobe Journey Optimizer. If the event payload does not contain an event id, it will be rejected by Adobe Experience Platform and it will not trigger a journey in Adobe Journey Optimizer. The other options are not valid or relevant causes why no people are entering a live journey with a system generated event.
The "Allow re-entrance" option is a journey property that defines whether customers can enter a journey more than once or not. This option does not affect how events are created or sent by external systems or applications. Profile attributes are properties that describe customer characteristics or behaviors, such as name, email, or purchase history. Profile attributes do not affect how events are created or sent by external systems or applications. References:
https://experienceleague.adobe.com/docs/journey-optimizer/using/journeys/create-a-journey.html?lang=en
https://experienceleague.adobe.com/docs/experience-platform/xdm/tutorials/create-event-schema-ui.html?