List all active absinthe subscriptions?

I am trying to trace a problem with pubsub. I confirmed, through logging, that subscription event should get triggered, but client is not receiving it. So I suspect that subscriber loses subscription somewhere along the way. It would be helpful to list all subscribers at the time the message is sent.

object :lock_subscriptions do
...
    field :lock_freed, non_null(:lock_result) do
      arg(:lock_input, non_null(:lock_input))

      config(fn
        %{lock_input: %{id: target_id, target_type: target_type}}, _ ->
          {:ok, topic: "#{@lock_freed_prefix}:#{target_type}:#{target_id}"}
      end)

      trigger(:release_lock,
        topic: fn
          %{success: true, id: target_id, target_type: target_type} ->
            "#{@lock_freed_prefix}:#{target_type}:#{target_id}"
            |> IO.inspect(label: "SUBSCRIPTION: LOCK-FREED triggered: ")

          other ->
            other |> IO.inspect(label: "SUBSCRIPTION: NOT FREED")
            "not-freed_do-not-publish"
        end
      )
    end