Json-server returning 404 when accessing custom route

Question

I'm trying to use json-server with custom routes, but they're all returning a 404.I can see that the routes.json file is being read, as well as the db.json file.

Here's the output from running json-server:

  Resources
  http://localhost:8000/check
  http://localhost:8000/custom-route

  Other routes
  /custom-route/me/ -> /custom-route

  Home
  http://localhost:8000

GET /check 304 2.994 ms - -
GET /custom-route/me/ 404 2.363 ms - 2

As you can see, json-server understands the custom route but it's not translating it. In the case of /custom-route/me, all I want is for it to end up in the same path, just without the /me.

Here's routes.json:

{
  "/custom-route/me/": "/custom-route"
}

And here's the part of db.json that refers to /custom-route:

  "custom-route": {
    "response": "check"
  },

What's going on and how can I fix it?