Can't return list of things from api workflow

Hi. I’m having trouble returning a list of credit card descriptions from the stripe.js @copilot plugin. My hope is to call bubble through the dropsource api then pull data from stripe and return it to the dropsource native iOS app. For some reason I cant get bubble to recognize the returned array from stripe as a list of arrays.

Stripe API has the card data within the customer object (sources).
https://stripe.com/docs/api/java#customer_object
https://stripe.com/docs/api/java#card_object

When I try to return the data it stays red in the function block per below:




I also tried to save the data to the bubble backend then return that but ran into the same issue in scheduling an API workflow:

Why isnt bubble accepting the list?