1. Check if you are using the correct sorting criteria. If not, select the desired criterion and select ‘Sort’ to apply.
2. Ensure ‘Group by’ categorization is selected. This will divide messages into groups organized by sender, subject, focus, or other ecological criteria.
3. Delete any message filters or rules that might be causing unintentional groupings.
4. Disable any sorting or grouping rules in Add-Ins.
5. Run a ‘Repair’ of your Microsoft Office Program to repair any faulty Outlook folders.