Question
Why are my new tickets created in Open status?
Answer
When you assign a ticket to a group with only one member, that agent becomes the ticket's assignee. A standard Zendesk ticket rule moves a ticket with an assignee from the New status to the Open status. This combination means new tickets can start in Open status rather than New status.
This interaction is why the Object | Ticket | Ticket | Is | Created condition is preferred over Object | Ticket | Ticket status | Is | New for triggers that fire at the time of ticket creation.
For more information, see About triggers and how they work.