Have you revoked any push notification certificates? Expo needs a valid, production push notification certificate – otherwise it’s impossible to send notifications. This error can also occur if you are using a Sandbox certificate. You must provide a push notification certificate for the production environment (see “certificate revoked” on Technical Note TN2265: Troubleshooting Push Notifications).
We recently (earlier today) tested creating a standalone app with Expo and verified that push notifications are working on iOS, so it appears likely that this is an issue with your push notification certificate. If you need further help, we also offer support plans (same-day, 8-hour, and proactive) here: Get Support — Expo.