Upsert-Mode= true doesn't work for DataSecurities API

Summary:

I am trying to fire DataSecurities REST API and the expectation of adding Upsert-Mode=true is that if the Data Security (DAS) already exists for said combination, it should be enabled if it exists but is disabled. But the API doesn't like it and keeps throwing "A record with this combination of values already exists"

Content (please ensure you mask any confidential information):

I am trying to fire DataSecurities REST API and the expectation of adding Upsert-Mode=true is that if the Data Security (DAS) already exists for said combination, it should be enabled if it exists but is disabled. But the API doesn't like it and keeps throwing "A record with this combination of values already exists"