[Python] Why is my Celery task stuck in RECEIVED state?

I'm going through Celery tutorial and I'm trying to use the "hello world" example:

from celery import Celery
from celery.utils.log import get_task_logger

app = Celery("src.my_module.tasks",
broker="amqp://guest:guest@localhost:5672/",
backend="redis://localhost:6379/0")

logger = get_task_logger(__name__)


@app.task
def add(x, y):
logger.info("Running add function with: %s, %s", x, y)
return x + y


I start Celery worker and Flower ui in powershell:

celery -A src.my_module.tasks worker --loglevel=info

celery -A src.my_module.tasks flower --loglevel=info

And btw. these are the docker container definitions for the brocker and result backend:

rabbitmq:
image: rabbitmq:3-management
environment:
RABBITMQ_DEFAULT_USER: guest
RABBITMQ_DEFAULT_PASS: guest
ports:
- "5672:5672"
- "15672:15672"

redis:
image: redis:alpine
restart: always
ports:
- "6379:6379"


Then I open up python console, import the add function and run: add.delay(1, 2). The terminal window in which I run Celery shows some output:

[2025-02-11 20:20:17,815: INFO/MainProcess] Task src.my_module.tasks.add[598610d9-3275-4996-bc81-065546677ae4] received

Aaaaand... That's it. The task never finishes, never even leaves the RECEIVED state. When I inspect it in Flower, I can see the arg, that status and result property which is None. Broker backend doesn't matter - both redis and rabbitmq say that the messages are unacked.

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