Backstop hangs on last scenario when using "readyEvent"

We've got a static Gatsby site running and we're using backstop for visual regression. For the most part it has been working pretty well for us.

One thing I wanted to improve is the hard coded delays that are in place via use of the `readyEvent` and so we implemented a console log accordingly. The problem that I have and cannot figure out is backstop appears to hang indefinitely when using `readyEvent`. At first I thought it would hang in random spots but then realized it was also hanging on the very last scenario as defined in the `backstop.json` file.

Things I've tried:
* Running with and without docker
* Running with an async capture and compare limit of 1 but this didn't help (it would still hang)
* Running a single scenario works fine with `readyEvent`

Has anyone else experienced this, looking for some insight.

Thanks