OSX Shell Runner: Can't pick up any jobs

Summary

Follow the install and registration instructions for the latest version of OSX runner, in shell mode-- try to start a matching job it pends forever.

Steps to reproduce

sudo gitlab-runner register
<... follow prompts, enter 'shell'>
cd ~
gitlab-runner install
gitlab-runner start

Tags: android ios mac osx unity unity3d

Then add a job with tag "unity".

Actual behavior

This job is in pending state and is waiting to be picked by a runner

Expected behavior

Job should be picked up by runner

Relevant logs and/or screenshots

Aug 21 17:19:10 aarons-mbp com.apple.xpc.launchd[1] (gitlab-runner): This service is defined to be constantly running and is inherently inefficient.
Aug 21 17:19:10 aarons-mbp gitlab-runner[810]: time="2018-08-21T17:19:10-07:00" level=warning msg="Running in user-mode."
Aug 21 17:19:10 aarons-mbp gitlab-runner[810]: time="2018-08-21T17:19:10-07:00" level=warning msg="Use sudo for system-mode:"
Aug 21 17:19:10 aarons-mbp gitlab-runner[810]: time="2018-08-21T17:19:10-07:00" level=warning msg="$ sudo gitlab-runner..."

Environment description

Custom installation on home macbook pro. Have verified that the process is running via gitlab-runner status

Used GitLab Runner version

$ gitlab-runner --version
Version:      11.1.0
Git revision: 081978aa
Git branch:
GO version:   go1.8.7
Built:        2018-07-22T07:24:45+00:00
OS/Arch:      darwin/amd64