When building an Advanced Outreach program in Journey Orchestrator, there are several points at which a small group of “Preview” participants will automatically be synced to the program. This occurs when you change the participants in a query, when you make changes to the Advanced Settings on the Audience, or when you duplicate an existing program. There is no way to stop the initial preview participant sync. 

I have been told that the expectation is that the time for this initial sync will take roughly 30 seconds, however in our instance there have been instances where this sync takes substantially longer. When the participants are syncing, no changes can be made to Advanced Settings or to the query itself. This can be a frustrating delay and inefficiency when working on multiple programs. I often have to duplicate an existing program to make changes to participants and I am frustrated by having to wait for participants to sync to the newly duplicated program before I can make any changes. Having the ability to stop the participant sync would be very helpful in these instances.