SLA holiday schedule is used that is to exclude the business holidays and stop SLA's from running.

If example, an additional holiday entry was being added on December 22nd for that day. It was added to this exception on the 22nd, but prior to the regular business hours. Unfortunately, though it created the exception, the SLAs still ran on the 22nd.

*It is noteworthy that the affected SLAs were already attached to task records prior to the schedule being created.  

No update was made on any of the affected records. Therefore, the "Run SLAs" business rule never ran in order to recalculate the affected SLAs.

There is a business rule called "Run SLAs." This business rule runs and checks to see if any recalculations need to be made to SLAs. The business rule is triggered when an update is made to the record (like the "category" field is changed, or the "assignment group" goes from blank to being populated with a value).

Both of the affected records were examined and, on the 22nd of December, neither one had an update to the incident record by a user that would kick off the Run SLAs business rule.

Alternatively, we can run "Repair SLAs" after the schedule is in place. This will allow the proper calculations to be made and values to be changed to reflect the new schedule.