[DefaultDragAndDropTarget] not working on ContentArea properties.

Description

Steps to reproduce

1. Create a block type with a content area property.
2. Decorate the content area property with [DefaultDragAndDropTarget].
3. Create a page type and add the block as a property, aka, a local block.
4. Render the block property so it’s editable on the page.
5. Create a page of the new page type.
6. Drag and drop another block onto the property.
7. Click the property to open the “fly-out” to see all properties in the local block/block as property.
8. Notice that the block got added to the content area in the fly-out, but it’s never rendered.
9. Save the page.
10. The block is gone from the content area.