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You need to convert the array into JSON string format first before you can map it into another JSON string.
To do this, you can try using the JSON “Transform to JSON” module —
Transforms any object to JSON.
For more information, see https://www.make.com/en/integrations/json, and https://www.make.com/en/help/app/json in the help centre.
Alternatively, you can use the built-in replace function.
For more information, do view these similar questions previously asked by other community members, which may answer your question:
Hope this helps! Let me know if there are any further questions or issues.
— @samliew
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