Hello, @crauss77.
Have you been able to find any users whose subscriptions are being affected by this problem? Because it could serve as an additional piece of information for Apple to use when investigating the problem.
And if you have stored the "latest_receipt" of any of their purchases, you could call the verifyReceipt URL to see if, at least, the purchase information that does not arrive as a notification is correctly registered with Apple.
Topic:
App Store Distribution & Marketing
SubTopic:
General
Tags: