Trouble setting up `vim-spec-runner` and `vim-tmux-runner`

I’m trying to set up the workflow mentioned in a recent Weekly Iteration episode.

I’ve installed both vim-spec-runner and vim-tmux-runner.

I’ve added this line to my vimrc to configure the runner:
let g:spec_runner_dispatcher = 'VtrSendCommandToRunner("{command}")'

I can’t get a new pane to open when I try to trigger the a spec run. I just see this error message: VTR: No runner pane attached.

The docs say a new pane should be opened if one isn’t already open:

2.1 VtrSendCommandToRunner~

Send a command to the tmux runner pane. This is the primary purpose of VTR. A new runner pane will be created.

Has anybody else tried this workflow?

I’ve fixed this, I managed to catch the plugin mid-refactor and some stuff hadn’t been updated.