Xero doesn't allow you to explicitly classify a contact as a "customer" or "supplier." It will only classify a contact as a "customer" when a sales invoice has been created for that contact. The same goes for suppliers - Xero only classifies a contact as a "supplier" once that contact has received an invoice.

This is a problem because a lot of people just want to create their customer contact in Xero and have it immediately imported into SortScape without having to first create an invoice. Therefore we can't ONLY import contacts that are considered "customers" by Xero. We also don't want to import suppliers if we know they are suppliers and not customers.

Because of this our algorithm imports Xero contacts that are either Customers or neither Customers nor Suppliers. In other words, we won't import customers that are just Suppliers.

This approach results in us potentially importing more contacts than needed but it's a lesser evil than NOT importing a contact that should be imported. And you can always archive a supplier if it does get imported in SortScape.

If a Xero supplier contact gets imported into SortScape...it is likely imported into SortScape because it was initially created as a Xero contact that was neither a Customer or Supplier.