Keep only data that is not currently in recipients?

I've 10 M records in recipients. 

Last time I did a "full" updated  based on "myfield" , there were 9.5M records updated but 0.5M were not. I guess because these 0.5M were not found based on "myfield". Since they were not present at the moment of the update, there was not match based on "myfield".

How can I only ingest this subsegment of new recipients?

I tried:

1) loading the file "my_recipients.csv.gz" with a Load Activity, 
2) Querying all the recipients where primary key (ID) is not empty.
3) Connecting those results in an exclusion activiy but I got: 

01/20/2025 9:14:16 AM WKF-560029 The document types of inbound events ('' and 'nms:recipient') are incompatible (step 'Exclusion'). Unable to perform the operation.
01/20/2025 9:14:16 AM Element 'target' unknown (see definition of schema 'Cargar Datos Persona (temp:fileImport)').
01/20/2025 9:14:04 AM Executing exclusion 'Nuevos recpients' (step 'Exclusion')

This is how my Exclusion activity is set, where Primary Set is the result of the branch where I load the my_recipients.csv.gz file. And the Exclusion Set is the query resulting with all the Recipients (with ID not empty).