Preview targetData for a specific recipient

Hello,
We are using targetData fields added in a workflow transition, as described in the Adobe documentation.

Use workflow data | Adobe Campaign

The delivery is configured with:
Recipients: Specified by the inbound event(s)
Action: Prepare
The fields are available in the transition and work during personalization, for example:
<%= targetData.nombreProducto %>
<%= targetData.importe %>

However, when we open the delivery Preview and select a specific recipient, recipient fields are displayed correctly, but targetData values return undefined.
Is it possible to preview the real targetData values associated with a specific recipient before sending the delivery? Is any additional configuration required in the delivery form or preview?

Thank you.