I have tried these variations, but always get all records:
filters=[{"field":"{fieldName}","operator":"is blank"}]
filters={"match":"and","rules":[{"field":"{fieldName}","operator":"is blank"]}
where {fieldName} matches the field in this URL parameter, which, which works correctly when loaded manually in a browser:
builder_table_filters={"match":"and","rules":[{"field":"{fieldName}","operator":"is blank","value":"","field_name":"{fieldLabel}"}]}
FYI, I am encoding the query parameters via URLEncoder.encode(filters, "UTF-8").
Thanks in advance for any/all help/advice!
Thanks,
Steve