flex.json list property - item_prompt_property not working, shows [object Object]

[delcorsets]

I am building a custom Basic architecture Flex Component (no MMX dependency) with a list property type using list_type: "group". I am trying to use item_prompt_property to display a label for each list item in the Page Builder UI, but it is not working as expected.

When item_prompt_property is set to any property code (e.g. "heading" or a dedicated "slide_name" text field), the list displays [object Object] instead of the property value as the item label.

When item_prompt_property is removed entirely, the list items display with no label at all - just a blank row with an arrow to open the item's properties.

My list property definition looks like this:

json

{
"code": "slides",
"prompt": "Slides",
"type": "list",
"list_type": "group",
"item_prompt_property": "heading",
"properties": [
{
"code": "heading",
"prompt": "Heading",
"type": "text"
}
]
}

Questions:

• Is item_prompt_property supported for Basic architecture components, or only for MMX/Shadows components?
• Is there a correct syntax for displaying a property value as the list item label in the Page Builder UI?
• Is there an alternative way to give list items a human-readable label so editors can identify slides without opening each one?