A client wanted to filter a column for blank values, and it wasn't working. I tried all sort of query syntax tricks with no avail. Is Exactly "", Is Not ?*, Is Exactly 0, Does Not Contain *, etc... The issue was that the field was a refRecId with a lookup against a related table. Here is what worked:
Use the 'Matches' option with the following value: (InventTable.FieldNameRefRecId == 0)
Include the parenthesis and change the field name to the field you are filtering on.
