Between 9pm Pacific and 9am Pacific, there was an issue with realtime notifications that caused delays of up to 12 hours for the notifications to be delivered.
This issue was resolved around 10am Pacific, and all pending notifications were delivered by 10:40am. As of 10:40am, all notification events are current, and delivery delays are down to normal (~100ms).
Apologies for the inconvenience. We have taken measures to prevent similar issues in the future.