Flask-SQLAlchemy Postgres query not inserting rows

I have the following code to insert data (detector_id, video_id, score) into the table score if it doesn't exist, and if it does exist, add the score to its existing value:

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = SQLALCHEMY_DATABASE_URI
db = SQLAlchemy(app)

query = "DO $$ BEGIN UPDATE "+table_score+" SET score = score + \'"+ concept_score +"\' " + \
        "WHERE detector_id = \'"+ detector_id +"\' AND video_id = \'"+video_id+"\'; " + \
        "IF NOT FOUND THEN INSERT INTO "+table_score+" VALUES (\'"+detector_id+"\', \'"+video_id+"\', "+concept_score+"); " + \
        "END IF; END $$;"
result = db.engine.execute(query)

This is equivalent to the following, which works when i execute it in pgAdmin:

DO $$ BEGIN 
    UPDATE score SET score = score + SCORE_VALUE
        WHERE detector_id = 'DETECTOR_ID' AND video_id = 'VIDEO_ID';
    IF NOT FOUND THEN 
        INSERT INTO score VALUES ('DETECTOR_ID', 'VIDEO_ID', SCORE_VALUE);
    END IF; 
END $$

However, it doesn't add anything if I try to execute the Python code. I also don't get any error messages. Other queries work fine so it is not a problem with my database connection. When I try to output list(result) it returns: This result object does not return rows.

If I do print query, and run the string in pgAdmin, it works. However, running it by db.engine.execute(query) does not. Other queries like SELECT * FROM score s WHERE s.detector_id ='DETECTOR_ID'; work fine with db.engine.execute(query). Does this have to do with the DO $$.. statement?

The following works fine, but seems undue:

query = "SELECT * FROM "+table_score+" s WHERE s.detector_id = \'"+ detector_id +"\' AND s.video_id = \'"+video_id+"\';"
result = db.engine.execute(query)
if len(list(result)) > 0:
    query = "UPDATE "+table_score+" SET score = score + \'"+ concept_score +"\' WHERE detector_id = \'"+ detector_id +"\' AND video_id = \'"+video_id+"\';"
else:
    query = "INSERT INTO "+table_score+" VALUES (\'"+detector_id+"\', \'"+video_id+"\', "+concept_score+");"
result = db.engine.execute(query)