"Stacked PRs are not enabled for this repository" even after being advised we are onboarded

[benrfairless]

We received the following email from Github 3 days ago:

We’re excited to onboard you to the private preview of GitHub Stacked PRs!

Stacked PRs has been enabled for all repositories under openaustralia.

However when I try to create a stack on openaustralia/righttoknow I get the following:

❯ gh stack submit
Checking stack state...
⚠ Stacked PRs are not enabled for this repository