Issue with using k-NN’s Painless Scripting functions for AWS Elasticsearch (7.10)

[Incrementing-coder]

"script": {
                "lang": "painless",
                "source": "1.0 + cosineSimilarity(params.query_value, params._source.use)",
                "params": {
                    "query_value": [...]
                }
            }
        }

Here is the script which I am using to do a cosine similarity between two vector fields having dimension of 512. The setting index.knn is set to false. I am getting this error which is basically not being able to cast the array list to KNN vector.

"root_cause": [ { "type": "class_cast_exception", "reason": "class_cast_exception: Cannot cast java.util.ArrayList to com.amazon.opendistroforelasticsearch.knn.index.KNNVectorScriptDocValues" } ]

Can someone help with this?