Could someone help me identify what might be causing this issue

pydub github page suggest doing following in order to debug

import logging
l = logging.getLogger("pydub.converter")
l.setLevel(logging.DEBUG)
l.addHandler(logging.StreamHandler())
# here do what you want with AudioSegment

this should reveal what is actually called.

D:\Python\Lib\site-packages\pydub\utils.py:170: RuntimeWarning: Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work
  warn("Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work", RuntimeWarning)

This is not error, but warning, generally this mean some anomaly was detected but program is still able to work, whilst error does result in halt.