In the response body we can see that the attachment is not created in ServiceNow and in payload we see the message:
"Could not find a record in table <table_name> with sys_id <sysID>".
The sys_id is the one of the record to be updated.
The issue is due to the system property glide.soapprocessor.large_field_patch_max having a default value of 512 KByte. This is an expected fixed value rather than a cut-off limit, therefore any attachment file with smaller size than this will not be created.
If you are using SOAP to perform the insert, the payload file size limitation is overridden by the value set in the system property glide.soapprocessor.large_field_patch_max.
When sending a file with a smaller size via the AttachmentCreator, the value should be set accordingly in the system property.
However, the AttachmentCreator SOAP web service is not recommended. Instead, use the REST Attachment API
to manage attachments with web services.
Related documentation page: AttachmentCreator SOAP web service
Limitations of the SOAP Attachment Creator webservice with Domain MSP