Tradfri gateway allows configuration, but then disappears. :(

I am trying to set up a tradfri gateway and a couple of bulbs.

I have discovery in my config file, and Home Assistant helpfully pulls up the configuration step and asks for the security key.
I provide it, but then the box disappears- No new group or switch appears, and the following error shows up in the log:

2018-06-14 21:25:51 ERROR (MainThread) [homeassistant.core] Error doing job: Task exception was never retrieved
Traceback (most recent call last):
  File "/usr/src/app/homeassistant/helpers/entity_platform.py", line 219, in async_add_entities
    await asyncio.wait(tasks, loop=self.hass.loop)
  File "/usr/local/lib/python3.6/asyncio/tasks.py", line 304, in wait
    raise ValueError('Set of coroutines/Futures is empty.')
ValueError: Set of coroutines/Futures is empty.

Can anyone help me discover what the issue is?

(I am running Home Assistant as a docker on unRAID.)

I have determined several things:

  1. Pairing bulbs with the hub without a ‘steering device’ (remote/dimmer) is either impossible, or extremely difficult
  2. The error I was seeing is a known bug with a fix in the works that occurs, as best I can tell, when HA looks for paired items even when none exist

Buying the $10 dimmer allowed me to pair the bulbs using the android app and HA saw them immediately.

I plan to return the Tradfri hub and dimmer once I am able to purchase a ConBee to replace them.