If your API call to retrieve data from the Airtable database was successful but the value for your variable returned empty, it could be due to a few reasons.
Firstly, ensure that you have correctly mapped your variable. The key should always start with "response.records", and using square brackets starting from index 0 to indicate which element to capture. For example, if you're trying to capture a task, your mapping might look like this: [response.record[0].fields.Task].
Secondly, check your "filterbyformula" for the Email. If the filter is too restrictive or not correctly set up, it might not return any data, resulting in an empty variable.
Lastly, confirm that the information you're sending to the Airtable is formatted correctly. Make sure that "records" and "fields" are exactly the two outer text key values, the column titles match the Airtable column titles exactly, and the column values match the Airtable expected data type.
If you've checked all these points and the issue persists, it might be due to a more complex problem that requires a deeper look into your project setup.