Required does not trigger validation when publishing with empty SEO field.

Steps:

1. Create CT and add SEO field.
2. Set the SEO field with "Required" set to true.
3. Leave SEO field placeholders empty.
4. Save CT.
5. Go to Content structure.
6. Create item using this CT.
7. Leave SEO fields empty.
8. Fill other required fields.
9. Try to publish.

Actual result: Item is published with empty required SEO fields.
Expected result: Validation prevents publishing.