When users are created, they are assigned to a Supplier Depot. If a user has been assigned to a supplier depot this can restrict their access to view only those suppliers selected in the Manage Depot set up. See notes here on How to add or update a depot.
If a user requires access to view all purchaser accounts, then their access can be changed to All Depots - Administrator.
In order to update an user profile you will require full Administrator access.
To update the users account, please follow the steps below:
Click on Administration tab on the left side menu.
Click on Manage Users.
Edit relevant user.
On the Details tab scroll to Supplier Depot and select the relevant access from the drop-down options.
Click on Update button.