Does anyone have any insight as to why a client-side navigation would seemingly hang during a Pages Router route change?

Debugging this kind of in real-time, but the details are loosely as follows:
- the breakage looks like the navigation is failing:
- we get a routeChangeStart event, but no corresponding routeChangeError or routeChangeComplete event. since we tie a progress indicator to this, the progress never completes
- network requests associated with the new page are sending and receiving as you'd expect so this isn't a server latency problem
- when broken, the existing page remains interactive, albeit in some odd ways:
- using any other links will correctly change the URL and a new route change will start and end (unclear if it's an error or success per the API), but the content on-screen doesn't change

This problem is intermittent but the incidence isn't low. It also only occurs in production and not in development.

Any thoughts about what contributes to behavior like this would help us greatly 🙂