Appdaemon not happy with service from custom component variable

I have HA version 0.114.2 and appdaemon version 4.0.5 and Python version 3.8.2. I have installed the rogro82/hass-variables custom component (integration). However, in making the service calls in my appdaemon apps, I see:

2020-08-21 15:00:01.007985 WARNING degreeDays: Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/appdaemon/", line 887, in worker
    funcref(self.AD.sched.sanitize_timer_kwargs(app, args["kwargs"]))
  File "/home/homeassistant/.appdaemon/apps/", line 65, in hourlyReset
    self.call_service('variable.set_variable', entity_id = 'variable.heating_degree_hours', value = round(hdh, 1))
  File "/usr/local/lib/python3.8/dist-packages/appdaemon/", line 195, in inner_sync_wrapper
    f = run_coroutine_threadsafe(self, coro(self, *args, **kwargs))
  File "/usr/local/lib/python3.8/dist-packages/appdaemon/", line 299, in run_coroutine_threadsafe
    result = future.result(self.AD.internal_function_timeout)
  File "/usr/lib/python3.8/concurrent/futures/", line 439, in result
    return self.__get_result()
  File "/usr/lib/python3.8/concurrent/futures/", line 388, in __get_result
    raise self._exception
  File "/usr/local/lib/python3.8/dist-packages/appdaemon/", line 1568, in call_service
  File "/usr/local/lib/python3.8/dist-packages/appdaemon/", line 1449, in _check_service
    raise ValueError("Invalid Service Name: {}".format(service))
ValueError: Invalid Service Name: variable.set_variable

If I look at the available service calls in the Developer tools/Services list, variable.set_variable is there. Not knowing whether this likely an appdaemon issue, custom component variable issue, or HA issue, I thought I’d start here.

Any help would be appreciated.