Even I am also facing the same issue
OperationFailure: PlanExecutor error during aggregation :: caused by :: embedding is not indexed as knnVector, full error: {‘ok’: 0.0, ‘errmsg’: ‘PlanExecutor error during aggregation :: caused by :: embedding is not indexed as knnVector’, ‘code’: 8, ‘codeName’: ‘UnknownError’, ‘$clusterTime’: {‘clusterTime’: Timestamp(1704818303, 1), ‘signature’: {‘hash’: b’\x9c\xae\xabc\x89D\x80\xc5PM\xd6\xf9\xfe\xbe\x82\xde\xe87\xd5\x05’, ‘keyId’: 7289444457848504322}}, ‘operationTime’: Timestamp(1704818303, 1)}