IFTTT not showing up after adding to config

I tried to add IFTTT to my config (Hass.io) like so:

ifttt:
  key: !secret ifttt_api_key

and then my 22-character IFTTT webhooks API key is defined in my secrets.yaml.

When I restart Hass.io (from the Hass.io tab 3-dot menu), and go to States (< >) in the sidebar when it comes back, ifttt doesn’t appear anywhere in the list of entities.

My log shows:

Error in logging
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/aiohttp/helpers.py", line 554, in __get__
    return inst._cache[self.name]
KeyError: 'remote'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/aiohttp/helpers.py", line 521, in log
    for key, value in fmt_info:
  File "/usr/lib/python3.6/site-packages/aiohttp/helpers.py", line 513, in <genexpr>
    for key, method in self._methods)
  File "/usr/lib/python3.6/site-packages/aiohttp/helpers.py", line 473, in _format_a
    ip = request.remote
  File "/usr/lib/python3.6/site-packages/aiohttp/helpers.py", line 556, in __get__
    val = self.wrapped(inst)
  File "/usr/lib/python3.6/site-packages/aiohttp/web_request.py", line 319, in remote
    peername = transport.get_extra_info('peername')
  File "/usr/lib/python3.6/asyncio/sslproto.py", line 306, in get_extra_info
    return self._ssl_protocol._get_extra_info(name, default)
  File "/usr/lib/python3.6/asyncio/sslproto.py", line 547, in _get_extra_info
    return self._transport.get_extra_info(name, default)
AttributeError: 'NoneType' object has no attribute 'get_extra_info'

Any thoughts?