In the case that two users have a certain role assigned to them, but one does not have access to, for example, all of the companies in the system, permissions may have not been appropriately set even though the user is given a role.

Go to Administration > Main > Users.

Highlight the user and click on Edit.

User company access, roles and permissions are configured in the area highlighted red below. In this case, you would be required to tick all the companies listed for the administrator to be able to have access to all companies.

Once the desired permissions are set, click Save in the toolbar to commit changes.