Applying single field may lead to erasing data in other fields

[ashklianko]

Was seen on the presentation with a Blog post content, when applying body text suggestion erased teaser text.

(EDIT) Way to reproduce:
Create empty content and generate any fields but not a display name, and insert couple of those; Close the AI Dialog and Open it again. Apply any of the previously generated fields again - other fields get erased.

The issue is that AI Assistant didn't get updated property tree after applying those fields.