Return Center is not shown in Zendesk app

Issue: 

When creating a return, not every Return Center is visible in the Zendesk app.

Explanation:

When creating a return, the list of Return Centers is specific to the Product(s) on the return.

Only those return centers that are configured for the product(s) on the return are shown in the list:

To Fix:

Add the Return Center(s) to the Product(s) in Settings - Products - Edit Product.

The product from the Zendesk return above is shown in Settings: