Tengo ptoblemas con un flujo en mi n8n

I have a workflow:
Cron → Google Sheets → OpenAI Chat node

Google Sheets returns 10 items.
Each item has a field called “idea”.

In the OpenAI node I use:
{{ $json.idea }}

Expected:
Generate one title per row.

Actual result:
The OpenAI node produces no output.
Message shown: “No output data returned”.

Question:
How should I configure the OpenAI node to correctly process multiple items from Google Sheets?
Do I need to enable item processing or use a loop?