Workers and route not working as expected

I have a worker set-up and a route for a bubble app to redirect a subfolder of /blog/ to a Wordpress blog hosted on Kinsta.

It’s not working though and I can’t work out why. In the preview on the worker code it loads as I would expect and loads the blog home page as it is set.

But when adding the route it just loads the existing bubble app page rather than the new one I want set up. Does anyone have any ideas on what might be causing it not to work?