Using serverless with yarn workspaces

Although I’ve had success using serverless-plugin-monorepo packaging up the hoisted dependencies, I’m still running into issues packaging up local packages not published to an external repo.

Local builds work fine, but serverless package errors with:

Error --------------------------------------------------

  yarn install --frozen-lockfile --non-interactive failed with code 1
  error An unexpected error occurred: "https://registry.yarnpkg.com/@private-package/foo: Not found".

I’m using serverless-webpack and it seems the issue lies with that plugin? I switched to serverless-jetpack and it packaged and deployed correctly, but I’d prefer to manage the packaging of the lambda with webpack for minification etc if possible.