The result of the flow is nullPayload if processing between os:store and os:retrieve takes 10 seconds. This is because the entry TTL of the object store is one second, which means that any stored value expires after one second and is removed from the object store. The expiration interval of 30 seconds only determines how often the object store checks for expired values, but it does not affect the TTL. Therefore, when os:retrieve tries to get the value after 10 seconds, it returns nullPayload because the value has already expired and been removed.
References:https://docs.mulesoft.com/object-store/osv2-faq#how-does-the-time-to-live-work