error starting, wrong URL

[rmfch]

I'm trying to use openconnect-sso to handle the azure/microsoft two step authentication when connecting to a cisco VPN server. Before the two step authentication was introduced, openconnect would work just fine.
I've installed openceonnect-sso without problems, but whenever I start it, it crashes with:

Traceback (most recent call last):
  File "/usr/local/bin/openconnect-sso", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.8/dist-packages/openconnect_sso/cli.py", line 169, in main
    return app.run(args)
  File "/usr/local/lib/python3.8/dist-packages/openconnect_sso/app.py", line 34, in run
    auth_response, selected_profile = asyncio.get_event_loop().run_until_complete(
  File "/usr/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "/usr/local/lib/python3.8/dist-packages/openconnect_sso/app.py", line 119, in _run
    profiles = get_profiles(Path(args.profile_path))
  File "/usr/local/lib/python3.8/dist-packages/openconnect_sso/profile.py", line 47, in get_profiles
    profiles.extend(_get_profiles_from_one_file(p))
  File "/usr/local/lib/python3.8/dist-packages/openconnect_sso/profile.py", line 29, in _get_profiles_from_one_file
    user_group=entry.UserGroup,
  File "src/lxml/objectify.pyx", line 234, in lxml.objectify.ObjectifiedElement.__getattr__
  File "src/lxml/objectify.pyx", line 453, in lxml.objectify._lookupChildOrRaise
AttributeError: no such child: {http://schemas.xmlsoap.org/encoding/}UserGroup

I noticed that the URL http://schemas.xmlsoap.org/encoding/ doesn't exist, but https://schemas.xmlsoap.org/soap/Encoding/ does. However, this string is encoded in the binary python file of openconnect-sso.

How can I correct this?
Thanks in advancd
Robert