I am experiencing this same problem -- works on 1 device and doesn't work on the other device. Where you able to figure out what the problem was?

Notifications received to our old endpoint -- https://oursite.com/appStoreV1 Ah, all of the notifications sent to the Version 1 endpoint are from before the cutoff. Our server logs indicate that we responded with a 200 so I wouldn't expect retries. We took a while to respond though (~8 seconds). Although that seems ridiculously long, that shouldn't impact whether these are retried, correct? Notifications received to our new endpoint -- https://oursite.com/appStoreV2 Version 1 Notifications received on this endpoint are also from before the cutover. We are currently responding with a 500 but I'm pushing a change to process Version 1 Notifications on our Version 2 endpoint.

What is your timeout? Thank you for your quick response on this!!