Resolved ticket stuck in personal queue

Can you please help me understand why in some instances “resolved” tickets appear to stay in the personal queue of the users? Is it a configuration error on our part?

Currently the minimum value for this metric is 1 day, once an email goes to “closed” any further communication from the customer results in an additional, follow-up case being created. By having the system wait 1 day to convert to close, this prevents follow up cases from being created immediately after an agent closes due to simple, yet common responses from customers: “Thank you”, “Have a Nice Day”, etc.