Finding Documents Containing Specific Empty Field

How to find documents containing a specific empty field while performing a search?

From the search bar,
- Click on Add Condition.
- Select the condition "By field".
- Select the field on which you want to perform your search.
- Select "does not contain"
- Add the following characters; ?*

Perform your search. This will find all documents where the field you have specified is equal to null.