Are private packages supposed to be supported?

[kurtextrem]

I have a package called @foo/bar, hosted at npm under an organization called foo. My ~/.npmrc looks like this:

//registry.npmjs.org/:_authToken=npm_<snip>
@foo:registry=https://registry.npmjs.org/

The ~/.yarnrc.yml:

npmRegistries:
  "https://registry.npmjs.org":
    npmAuthToken: npm_<snip>
npmScopes:
  foo:
    npmAuthToken: npm_<snip>

I used yarn npm login --scope foo --web-login to login. Running yarn then results in this error:

yarn
➤ · Yarn 6.0.0-rc.13
➤ ┌ Installing packages
➤ │ @foo/bar@npm:1.0.0: Network error: HTTP status client error (404 Not Found) for url (https://registry.npmjs.org/@foo%2fbar/-/bar-1.0.0.tgz)

Works with npm and yarn stable. Am I missing something?