Flower loads indefinitely

[CharlesFr]

Describe the bug
http://localhost:5557/ loads indefinitely despite flower starting as expected

To Reproduce
Steps to reproduce the behavior:

1. Start flower

celery -A project_name \
    --broker="redis://redis:6379/0" \
    flower

2. Navigate to http://localhost:5557/
3. Page is stuck in infinite loading and remains blank

flower is being launched as part of a docker-compose django application with 6 other containers (inc redis, beat and celery), which are all starting as expected.

Expected behavior
Expecting flower dashboard to load which does not happen

running ps aux inside the container I can see that flower is running:

root@36ea937babc1:/app# ps aux | grep flower
root           1  0.0  0.0   5488  3244 ?        Ss   16:34   0:00 /bin/bash /start-flower
root         111  9.5  0.8 1807884 283864 ?      Sl   16:35   0:26 /usr/local/bin/python /usr/local/bin/celery -A project_name --broker=redis://redis:6379/0 flower --basic_auth=admin:admin --loglevel=DEBUG
root         156  0.0  0.0   4836   892 pts/0    S+   16:40   0:00 grep flower

Netstat also looks healthy:

root@36ea937babc1:/app# netstat -tuln | grep 5555
tcp        1      0 0.0.0.0:5555            0.0.0.0:*               LISTEN     
tcp6       0      0 :::5555                 :::*                    LISTEN 

System information

root@9b4a75cf222c:/app# python
Python 3.11.4 (main, Jun 13 2023, 15:34:37) [GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from flower.utils import bugreport; print(bugreport())
flower   -> flower:2.0.1 tornado:6.3.3 humanize:4.8.0
software -> celery:5.3.4 (emerald-rush) kombu:5.3.2 py:3.11.4
            billiard:4.2.0 py-amqp:5.2.0
platform -> system:Linux arch:64bit
            kernel version:5.15.133.1-microsoft-standard-WSL2 imp:CPython
loader   -> celery.loaders.app.AppLoader
settings -> transport:amqp results:disabled

deprecated_settings: None

Flower logs:

PostgreSQL is available
2023-12-27T16:13:54.392428992Z LOG_LEVEL is set to: DEBUG
2023-12-27T16:13:56.941536552Z reading envs from local .env/.dev-sample file
2023-12-27T16:13:57.969751554Z Error: No nodes replied within time constraint
2023-12-27T16:13:58.348600138Z Celery workers not available
2023-12-27T16:14:01.624674403Z reading envs from local .env/.dev-sample file
2023-12-27T16:14:02.647502284Z Error: No nodes replied within time constraint
2023-12-27T16:14:02.945831862Z Celery workers not available
2023-12-27T16:14:06.075034301Z reading envs from local .env/.dev-sample file
2023-12-27T16:14:06.098401611Z ->  celery@adda0216ba83: OK
2023-12-27T16:14:06.098426286Z         pong
2023-12-27T16:14:07.102304098Z 
2023-12-27T16:14:07.102352357Z 1 node online.
2023-12-27T16:14:07.413457500Z Celery workers is available
2023-12-27T16:14:08.759771261Z [I 231227 16:14:08 utils:148] Note: NumExpr detected 16 cores but "NUMEXPR_MAX_THREADS" not set, so enforcing safe limit of 8.
2023-12-27T16:14:08.759827480Z [I 231227 16:14:08 utils:160] NumExpr defaulting to 8 threads.
2023-12-27T16:14:09.527725149Z reading envs from local .env/.dev-sample file
2023-12-27T16:14:12.088229507Z 27-12-23 16:14:12.087 - INFO: Visit me at http://0.0.0.0:5555 (command.py:168)
2023-12-27T16:14:12.097123388Z 27-12-23 16:14:12.096 - INFO: Broker: redis://redis:6379/0 (command.py:176)
2023-12-27T16:14:12.259837427Z 27-12-23 16:14:12.259 - INFO: Registered tasks: 
2023-12-27T16:14:12.259866198Z ['celery.accumulate',
2023-12-27T16:14:12.259870564Z  'celery.backend_cleanup',
2023-12-27T16:14:12.259872604Z  'celery.chain',
2023-12-27T16:14:12.259874574Z  'celery.chord',
2023-12-27T16:14:12.259876489Z  'celery.chord_unlock',
2023-12-27T16:14:12.259878651Z  'celery.chunks',
2023-12-27T16:14:12.259880566Z  'celery.group',
2023-12-27T16:14:12.259882466Z  'celery.map',
2023-12-27T16:14:12.259884382Z  'celery.starmap',
2023-12-27T16:14:12.259919807Z  'project_name.celery.divide',
2023-12-27T16:14:12.259921830Z  'project_name.celery.sleepy_task_test'] (command.py:177)
2023-12-27T16:14:12.272942524Z 27-12-23 16:14:12.272 - INFO: Connected to redis://redis:6379/0 (mixins.py:228)

[CharlesFr]

The above issue only occurs on python >3.9 - is this expected?