With Web Helpdesk, the hours are business hours, not actual hours. What business hours have you defined within your overall ticketing system? Usually this would be 3 days (24 business hours over 8 hours per day). Given that those tickets were set on the 31st, this would be the end of that 24 business hours, so based on the time they were set to Resolved, the tickets should start closing. If you were wanting more 24 hours, rather than 24 business hours, then you may want to put 1 business day rather than using the hours.