hapi-swagger returning JSON data but no UI

Question

My routes contain the the 'api' tag

... 
{
  method: 'GET',
  path: '/blah/albums',
  options: { tags: ['api'], handler: myHandlerFunction }
},
...

and I am including the Inert, Vision, and hapi-swagger plugins

import Hapi from '@hapi/hapi'
import Inert from '@hapi/inert'
import Vision from '@hapi/vision'
import HapiSwagger from 'hapi-swagger'
...
  const plugins = [
    Inert,
    Vision,
    {
      plugin: HapiSwagger,
      options: swaggerOptions
    },
...

When I hit the /swagger.json endpoint I get the correct JSON data, but when I hit the /documentation endpoint like the documentation says I get a {"statusCode":404,"error":"Not Found","message":"Not Found"}