trying to get a null filter

[Bruno Brendel Gomes]

In the issues, there's a field where it can pull a value or bring up those that are empty.

We've tried various ways to pull a filter that identifies empty fields, but we haven't been successful. Identifying the tickets with this empty field is of fundamental importance to solve future issues.

How to solve this problem?

[Matthew Lempitsky]

From the looks of your screenshot, it appears that the field you are trying to find the null values for is a custom field that is present
in the Issue Field table. This table only has rows for values that ARE present and does not contain "empty" or null rows for issues that 
do not contain a value. 

The way around this is to create a custom table for the field in question. 

You can use this approach (substitute for your field in question) In my example, I am using the field Story Points:

You will then have to ensure there is a foreign key relationship created for the issue_id column in your new custom table and that of the standard Jira Issue table.

You will then be able to use visual SQL to query where this column is NULL. This works because this table results in a row for every issue in the issue field table and creates the null value during the aggregation: