Try this for downloading an ActiveInventoryReport using lmslib

gistfile1.py

"""
This is an example of requesting a report through LMS, in this case we're
requesting an ActiveInvenotryReport.

NOTE: This code is completely untested at this point, but it should work.
"""

import uuid

import lmslib

# Always test with the Sandbox environment first :)
env = lmslib.SANDBOX

# Create a StartDownloadJob LMSCall object and give it the environment.
start_dl = lmslib.StartDownloadJob(env)

# I think listing type is one of "Auction", "AuctionAndFixedPrice", "FixedPrice"
start_dl.buildRequest("ActiveInventoryReport", uuid.uuid4(), listingType="Auction")

response_string = start_dl.sendRequest() # The xml response from eBay. Use this directly if you want to parse it yourself.

# If I remember correctly, this step was just used for some minor parsing of the 
# response to determine if it was a success or error response.
# I know the parsing is pretty crap at this point, I never got around to
# writing a more complete parser for these responses.
response, resp_struct = start_dl.getResponse()


# Basically you'll want to parse the response and determine if you can
# go on to the next step (which requires a jobId).
if response == 'Success':
	jobId = resp_struct.get('jobId', None)


# Now that you've got a jobId, you'll want to retrieve the job's status
# until it returns "Completed" and gives you a downloadFileId.

job_status = lmslib.GetJobStatus(env)
job_status.buildRequest(jobId)

downloadFileId = None # Placeholder for download file id.

while True:
	response = job_status.sendRequest()
	response, resp_struct = job_status.getResponse()

	if response == "Success":
		if resp_struct[0].get('jobStatus', None) == 'Completed':
			# Job is finished, so get the download file ID
			downloadFileId = resp_struct[0].get('fileReferenceId', None)
			break

	time.sleep(5) # Don't spam the ebay server with too many requests at once


if downloadFileId:
	# Now that the report has finished, download it.
	download_file = lmslib.DownloadFile(env)
	download_file.buildRequest(jobId, downloadFileId)

	response = download_file.sendRequest()
	response, resp_struct = download_file.getResponse()

	if response == 'Success':
		print resp_struct # Download should be in the struct.

Thank you after 8 years.