Seems to be a issue with multiple builds, not cleaning cache directory and using middleware.
Delete .next if exists
Run:
npm run build && npm start
Open: http://localhost:3000/test so that the html will cache in .next/cache
Terminate server
Run again:
npm run build && npm start
Open: localhost:3000/test
Console shows: Error: Failed to load static props. As it is trying to load _next/data with a different build id
There are also failed network requests.