ReadyEvent not detected within readyTimeout limit. (30000 ms) https://local.ddev.site

When I run

`backstop reference --config="backstop.config.js"`

I get the error in the title:

`ReadyEvent not detected within readyTimeout limit. (30000 ms) https://local.ddev.site`

I'm not entirely sure what might be causing this and why. The reference images are being generated from a different, live site which is set in the config as:

`"referenceUrl": "https://mylivesite.co.uk/",`

I wonder why this might be occurring and if there's a fix for it? I'm not 100% sure why the local site is being called during the reference generate stage for a different URL.

Thanks!