Why is the sum of SLA tickets different from the sum of Achieved, Breached, and Active SLA tickets?
The sum of Achieved, Breached and Active SLA tickets is different from SLA tickets sum because the calculation for each metric is different. The SLA tickets metric counts tickets if an SLA target is present on a ticket while Achieved, Breached, and Active SLA tickets metric counts the tickets based on the status of the SLA target.
A ticket could have multiple targets applied to it that are active, breached, and achieved simultaneously.
For example, a ticket has a first reply target that was breached and an agent response time target that is currently active. SLA tickets metric counts this as one while Breached SLA tickets, as well as Active SLA tickets, counts this as one each.
For more information about defining and using SLA policies, see the article: Defining and using SLA policies (Professional and Enterprise).
For more information about SLA metrics and attributes, see the article: Metrics and attributes for Zendesk Support.