Cannot run background job with exq

I found post about running Exq in elixir app:

I installed redis
I installed exq
I added exq config:

config :exq,
  host: "",
  port: 6379,
  namespace: "exq",
  concurrency: 8,
  queues: ["default"],
  poll_timeout: 50,
  scheduler_poll_timeout: 200,
  scheduler_enable: true,
  max_retries: 25

After opened exlir console I type: Exq.start_link but I received {:error, {:already_started, #PID<0.242.0>}}. I have checked more details:

> {:error, {:already_started, pid}} = Exq.start_link # {:error, {:already_started, #PID<0.242.0>}}
> Process.alive?(pid) # true
[registered_name: Exq.Sup, current_function: {:gen_server, :loop, 6},
 initial_call: {:proc_lib, :init_p, 5}, status: :waiting, message_queue_len: 0,
 messages: [],
 links: [#PID<0.245.0>, #PID<0.247.0>, #PID<0.253.0>, #PID<0.254.0>,
  #PID<0.252.0>, #PID<0.246.0>, #PID<0.243.0>, #PID<0.244.0>, #PID<0.241.0>],
 dictionary: ["$ancestors": [#PID<0.241.0>],
  "$initial_call": {:supervisor, Supervisor.Default, 1}], trap_exit: true,
 error_handler: :error_handler, priority: :normal, group_leader: #PID<0.240.0>,
 total_heap_size: 6771, heap_size: 2586, stack_size: 9, reductions: 982,
 garbage_collection: [min_bin_vheap_size: 46422, min_heap_size: 233,
  fullsweep_after: 65535, minor_gcs: 1], suspending: []]

Unfortunatelly when I want to run exq job from mix task then I receive:

** (exit) exited in:, {:enqueue, "default", SampleWorker, [123]}, 5000)
    ** (EXIT) no process
    (elixir) lib/gen_server.ex:596:
    (elixir) lib/enum.ex:651: Enum."-each/2-lists^foreach/1-0-"/2
    (elixir) lib/enum.ex:651: Enum.each/2
    (mix) lib/mix/task.ex:296: Mix.Task.run_task/3
    (mix) lib/mix/cli.ex:58: Mix.CLI.run_task/2
    (elixir) lib/code.ex:363: Code.require_file/2

Maybe someone can help me and tell what should I do or what I am doing wrong.

Sounds like either its interface is being used wrong or misconfigured or internal bug. Can you make a minimal reproducable case and put on github?

I observed strange thing. After restart computer (OS X) when I try run exq manual with Exq.start_link then I always receive already started. I have prepared minimal exq config with once worker:

I opened elixir console and then I type:

iex(0)> Exq.start_link
{:error, {:already_started, #PID<0.237.0>}}
iex(1)> Exq.enqueue(:exq, "default", "SampleWorker", [])
** (exit) exited in:, {:enqueue, "default", "SampleWorker", []}, 5000)
    ** (EXIT) no process
    (elixir) lib/gen_server.ex:596:

I think the verbage you want is Elixir.Exq.enqueue based on the readme.