Docker servers pre-loaded script is not executed.

I'm using the next docker-compose configuration:

pgAdmin:
  image: dpage/pgadmin4
  ports:
    - "5050:80"
  environment:
    PGADMIN_DEFAULT_EMAIL: user@domain.com
    PGADMIN_DEFAULT_PASSWORD: secret
  volumes:
    - ./servers.json:/pgadmin4/servers.json

After run the docker, if I execute the next command:

$ docker exec pgAdmin cat servers.json 

the servers have been copied properly but the command:

is NOT executed so I haven't the servers available in the app. I've seen it the github (https://github.com/postgres/pgadmin4/blob/master/pkg/docker/entrypoint.sh).

If I execute manually the command (docker exec -it toolbox_pgAdmin_1 python setup.py --load-servers output_file.json --user user@domain.com) works properly (for this reason I suspect the entrypoint.sh is not working properly or not found the python part).

Why is not executed and if I do manually is ok?

Thank you very much!