osTicket Version v1.15.2
Web Server Software Apache/2.4.41 (Ubuntu)
MySQL Version 8.0.27
PHP Version 7.4.3

Dear osTicket community,
I am facing an issue with my osTicket installation. Whenever a new ticket is created, it is flagged as overdue almost immediately. I have checked the SLA, the schedule and all and tried increasing the SLA time which currently it is like 30 hours but the problem still exists.
I do not know if it is relevant but this problem was not always there. For example for about 6 months operating the helpdesk and even after applying an update in osTicket it worked correctly. The problem exists for about 4 months now and I could not relate it with an update in PHP or something like that.
Has anyone face the same issue and how did you solve it?
Thank you in advance.