*Advanced Partner Centers have Partner restrictions set to "Own and Subordinates" by default.*
By design, the Advanced Partner Center Role will only see their own Support Cases or the Cases submitted by their Child Partners.
Should the setting to view cases from other Partners be needed, a Custom Advanced Partner Center Role should be created and Partner Restrictions should be modified (either set Allow Viewing = T or change the restriction completely, as required).
As an Administrator:
1. Navigate to Setup > Users/Roles > Manage Roles.
2. Customize the Advanced Partner Center Role.
3. Provide a Label
4. Set Allow Viewing = T or Partner Restriction to 'none - no default' or 'none - default to own', depending on the restriction requirement.
5. Save and apply the Custom Advanced Partner Center Role to the Partner that is supposed to see all Cases.
The setup defined above can be used to create a Main Partner that can monitor cases for Partners, therefore acting as a Support system for Partners.