Calender is being overlooked for Tender Response

We have set up 2 hours for a carrier as a response and attached a calendar of working hours from 8.30 am to 5 pm. The tender was being sent to the carrier at 4 am, and since the calendar was set, the carrier must have until 10.30 am to respond. However, the tender expired at 6 am not giving a chance for the carrier to respond.

Please help with what needs to be done. Checked the carrier setup, location, and calendar associated with the carrier and everything is set the same. It only affects one carrier.