Short answer: notifications that arrive late after an iOS 27 update are usually being held rather than lost. The common holders are a Focus mode filtering what may interrupt you, Scheduled Summary batching notifications into set times, a per-app notification setting, or Low Power Mode reducing background activity. Apple's push service is a system-level channel, so a broken push channel would mean notifications never arrive at all.
That distinction — late versus never — is the whole diagnosis, and it decides which half of this article you need.
Late and never are different problems
| What you see | What it means | Where to look |
|---|---|---|
| Notifications appear, but minutes or hours after the event | Delivered, held or batched | Focus, Scheduled Summary, Low Power Mode |
| They appear only when you open the app | Not delivered as push at all | The app's permission, its version, its own settings |
| One app is late, the rest are fine | That app's settings or adaptation | That app's notification settings |
| Everything including Messages and calls is late | System-level or network conditions | Focus, Low Power Mode, signal, restart |
The first and second rows have almost nothing in common. In the first, iOS already has the notification and is choosing when to show it. In the second, the notification never reached the phone as a push, and the app fetched it when you opened it. Mixing these up is the main reason people spend an hour on the wrong screen.
If your situation is the second row — nothing shows until you open the app — the checks are in iOS 27 notifications not showing.
Why push and Background App Refresh are separate
This is worth stating plainly, because it is the most common mix-up in this whole area. Push is Apple's system-level channel: the app's server hands the message to Apple, Apple delivers it to the device, and iOS presents the notification. Background App Refresh is a different mechanism that decides whether an app may wake on its own and fetch fresh data while you are not using it.
Two consequences follow. First, turning Background App Refresh off to save battery does not make you miss pushes — the push still arrives. Second, if notifications are genuinely not arriving, turning background refresh off will not help, because it was never the delivery path. The mechanism is explained in What is Background App Refresh?.
The checks, in order
① Focus modes. Open Settings → Focus and look for any mode that is or was active — Do Not Disturb, Work, Sleep, Personal. A Focus filters notifications against its allowed people and apps list, and anything not on that list is silenced or delayed. Check the allowed lists inside each mode, because a mode that looks off in your habits can still be scheduled.
② Scheduled Summary. In Settings → Notifications → Scheduled Summary, check whether it is on and which apps are included. Included apps have their notifications collected and delivered at the times you set, which feels identical to "notifications stopped working". Move anything time-sensitive out of the summary.
③ Per-app permission and alert style. In Settings → Notifications, open the app and confirm Allow Notifications is on and the alert style is not None. An update can occasionally re-ask for permission, and if the prompt was dismissed with "Don't Allow", the setting stays off.
④ The app's own switches. Many apps keep a second layer of notification settings — a mute switch, a quiet-hours window, or a Wi-Fi-only rule. System settings being correct does not mean the app's own switches are on.
⑤ Low Power Mode. In Settings → Battery, check whether Low Power Mode is on. It reduces background activity, which can hold back anything that depends on background work, and its trade-offs are described in What is Low Power Mode?.
⑥ Signal and network conditions. A phone with a weak cellular signal can receive pushes late, and this often shows up as "late at work, fine at home". Compare the two locations before assuming a software cause.
⑦ Restart, then update. A normal power off and on clears stuck state cheaply. If a single app is late while everything else is punctual, update that app: third-party apps adapt to a new system on their own schedules, and this is the same pattern described in Only one app crashing after the update.
When it is genuinely a problem
- Messages and calls are late too, on a good network, after a restart, with no Focus or summary active — this is closer to a system or carrier condition, and updating to the latest minor version or contacting Apple is a reasonable next step.
- One app is consistently late and updating it changes nothing — that is the app's server or its adaptation, and its developer is the right recipient of the report.
- Notifications are punctual on Wi-Fi and late on cellular — the difference points at the network or at power policy holding background work back, not at the notification system.
One thing to avoid: do not install configuration profiles or third-party tools that claim to "repair" or "boost" push. Push is an Apple system-level channel; nothing external can speed it up, and the settings above are the real entry points.