Why does log.debug() not log when the level is set to logging.DEBUG?

You haven't configured the logging system, so it's still using the defaults (level WARN for the root logger).

https://docs.python.org/3/library/logging.html#logging.basicConfig says basicConfig

Does basic configuration for the logging system by creating a StreamHandler with a default Formatter and adding it to the root logger.

Configuring the logging system with basicConfig first will create a handler and formatter that your logger will use:

logging.basicConfig()
log = logging.getLogger('hello')
log.setLevel(logging.DEBUG)
print(log.getEffectiveLevel())
log.debug('debug log')
log.critical('critical log')

Outputs:

10
DEBUG:hello:debug log
CRITICAL:hello:critical log

In Logger.callHandlers, each handler compares the log record's level with its level. If there aren't any handlers, it will use the default of WARNING.

With a StreamHandler it will

sends logging output to streams such as sys.stdout, sys.stderr or any file-like object"

according to the documentation

import logging 
import sys

# Initialize Logger and set Level to DEBUG
logger = logging.getLogger()
logger.setLevel(logging.DEBUG)

# Initialize a Handler to print to stdout
handler = logging.StreamHandler(sys.stdout)

# Format Handler output
logFormatter = logging.Formatter(
    "%(asctime)s %(message)s", datefmt="%m/%d/%Y %I:%M:%S %p"
)
handler.setFormatter(logFormatter)

# Set Handler Level to DEBUG
handler.setLevel(logging.DEBUG)
logger.addHandler(handler)

logger.debug('Debug Info')
>>> 09/19/2020 09:01:00 PM Debug Info

You need to add stream handler

import logging

log = logging.getLogger('hello')
log.setLevel(logging.DEBUG)

# # Create a file handler to store the logs
file_handler = logging.FileHandler('test.log')
log.addHandler(file_handler)

# # Send output to terminal
stream_handler = logging.StreamHandler()
log.addHandler(stream_handler)

log.debug('debug log')