Can't enable autoscaling on private space dynos via CLI

[j-caro]

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

When using the Heroku CLI to enable autoscaling for private space web dynos, I receive an error that autoscaling is only available with Performance Dynos

heroku ps:autoscale:enable --app=<PrivateSpaceAppName> --min=2 --max=4 --p95=1000
Enabling dyno autoscaling... !
Error: Autoscaling is only available with Performance dynos
    at Enable.run (C:/Program Files/heroku/client/node_modules/@heroku-cli/plugin-ps/lib/commands/ps/autoscale/enable.js:22:19)

I'm can enable autoscaling for the same app in the dashboard with no issues.

What is the expected behavior?

We should be able to enable autoscaling for private space dynos from the CLI

Heroku Version:

heroku --version
heroku/7.29.0 win32-x64 node-v11.14.0