As an administrator, you do not have access to all companies. There is a special permission called View Global Company List. This will allow administrators to do the following:
Add new companies
See all companies in the specific instance
See all the users from all companies on the user summary screen
If you do not have this permission, please contact ProcessPro support and, if you are eligible, we can add it.
If you have this permission, you can add the permission to other users and administrators within your instance.