Issue #3352822: Paragraph parent entity property is empty when adding new paragraphs

src/Form/InsertComponentForm.php

@@ -110,8 +110,11 @@ class InsertComponentForm extends ComponentFormBase {
       $this->paragraphDefaults = $paragraph_defaults;
     }
     $this->setLayoutParagraphsLayout($layout_paragraphs_layout);
-    $langcode = $this->layoutParagraphsLayout->getEntity()->language()->getId();
+    $parent_entity = $this->layoutParagraphsLayout->getEntity();
+    $langcode = $parent_entity->language()->getId();
+    $field_name = $this->layoutParagraphsLayout->getFieldName();
     $this->paragraph = $this->newParagraph($paragraph_type, $langcode);
+    $this->paragraph->setParentEntity($parent_entity, $field_name);
 
     $this->parentUuid = $parent_uuid;
     $this->region = $region;