I've just received an answer from Apple Developer Technical Support regarding this "lost silent push" issue, which is confirmed on not only iOS 14 betas but also the public version of iOS 14 (18A373).
The summary is as follows.
This behavior is expected and is already implemented in the versions before iOS 14.
For background push, which is sent as priority 5 (low priority), it has always possibilities to be throttled from the resource efficiency perspective including battery consumptions.
That is, background push is never guaranteed to be delivered to the app every single time.
This "throttling" schedule method is sometimes fine tuned by updating iOS versions. (like this times...)
The possible solution for this issue is to use Notification Service Extension, which can be used only for visible push though.
Hmm, hope this helps...
Topic:
App & System Services
SubTopic:
Notifications
Tags: