Search: Find Items where Field or Layer is Empty

This will find all Content Items where the field is not present, but also those without the Layer assigned, so you must additionally check if the Layer present.

-_exists_:fieldpath

To check if a field is not available use exists and a dash in front of it: -exists (not exists)
- This functionality is similar to the NOT Filter with the Exists Filter
Find the fieldpath of the field you are looking for: layerId.fieldId
The syntax is based on Elastic Search Boolean Operator Logic: https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-query-string-query.html#_boolean_operators

-_exists_:corporateInformation.title.en