Can't generate Dynamic Children from a Data Type (converted from a JSON)

I'm trying to follow the process from the https://docs.flutterflow.io/resources/backend-logic/rest-api ("Create Custom Data Type matching to JSON structure" section)

Here are my data types

And here's my Supabase table, from which I make an API Call

Here's what I get when I test the API

When I try to convert this JSON response to a Data Type "Schedule" and then generate Dynamic Children from the Items of this type (I check "Is List" in Parse as Data Type section)

Then It all generates correctly

And here's how an Item in "schedule_date" List is generated

But when I try to the the exact same thing as It is show in the documentations (the link that I attached at the beginning): not generate Dynamic Children from the List of "bigger" Data Type Schedule, but make the Data Type Schedule not a List, and Generate children from the List "schedule_data" (Data Type Lessons), which is inside the item of a Data Type Schedule

It shows me that the list is empty, though when I generated it from Schedule items it wasn't empty

(I have checked Save at the API page)