I'm working as Jira administrator in my company, and we faced a problem after setting up a new holiday.
The problem is related mainly to "Time to first response" SLA, as it most of the time breach although the responsible teams act rapidly to all tickets -sometimes within 10 minutes-.
We tried to make a re-index for the affected projects, update the calendar and refresh the SLA, but we didn't succeed in fixing the problem.
Please let me know if there is any solution for this problem that we can try.