iCloud Sync not working with iPhone, works fine for Mac.

For debugging purpose, would you mind to check if it's that the macOS app failed to export data to CloudKit, or that the iOS app failed to import from CloudKit? The detailed steps to do the check are documented here.

Best,
——
Ziqiao Chen
 Worldwide Developer Relations.

-It is the iPhone not receiving the notification to update.

Steps to reproduce

• Change property on Mac
• iPhone app is active, no changes received (even after 2 hours)
• Swipe to home screen on iPhone
• open iPhone app
• SwiftData syncs on iPhone and shows changes that were made on the Mac

(Again, this worked 48 hours ago, and the only change that was made was updating all devices to iOS26.4)

Just to add one more piece to this...

Make a change on the Mac

• AppleTV makes the change instantly
• Apple Watch makes the change instantly
• iPhone only updates after you leave the app and launch it again
• iPad only updates after you leave the app and launch it again

I have the same issue and filed a bug report already: FB22324179

Since updating to iOS 26.4, iCloud remote notifications (CloudKit push notifications) are no longer delivered. The same setup worked reliably on iOS 26.3 without any changes to the app or server configuration, so this a new regression from Apple.

didReceiveRemoteNotification: in AppDelegate gets not called anymore.

I also did notice the same issue, I have a device that still running iOS 26.3 and another one with 26.4, when I make a change the 26.3 get the background notification and update the data but on the device with 26.4 it is not working. I tested also watchOS 26.4 it is working perfectly the notification is processed.

I don't know if it's related, but my sample iOS app (iOS 18.5) doesn't receive a remote notification today in line with CKQuerySubscription, which it received yesterday.

The same happened for me, today (and played with updated on multiple devices to confirm).

sync 26.3 -> 26.3 => 100%

sync 26.4 -> 26.3 => 100%

sync 26.3 -> 26.4 => 0%

sync 26.4 -> 26.4 => 0%

Thank you for reporting the issue, which does seem like a regression in iOS 26.4.

Given the extensive impact of the issue, I’d suggest that you file a feedback report, if not yet, to attract more attention from the relevant engineering team.

Specific to the issue, you don't need to capture a sysdiagnose to file a feedback report, but please mention the user impact in your report, if you don't mind. Please share your feedback report ID here. Thanks again.

Best,
——
Ziqiao Chen
 Worldwide Developer Relations.

Bug report Filed - FB22343127

Bug reported FB22343088

FB22343668

Failure occurs whether I add or change a record on the Owner device or the Shared device. I verify the iCloud database is correct. Deleting and reinstalling the app downloads the correct data.

I’m experiencing the same issue on my end. Can’t test with iOS 26.3 anymore, but it works as expected on iOS 18.7.2 and macOS 15.7.4. On iOS 26.4 I’m not receiving any remote notifications, so updates are only fetched when I relaunch the app. Using CKSyncEngine under the hood.

I am having this same problem and it appears to have started right when upgrading to 26.4. One tester has this problem as well (also on 26.4) however another tester on 26.4 does not. So it's possibly not affecting everyone, but it's affecting me now and I just wasted an entire day on this assuming it was my code because I had changed some subscription stuff the day before. And then I spent half of today on this problem, too, trying everything including reverting back to code from many days ago all to no-avail.

So on the one hand, reassuring it's not just me. On the other hand.... arghhh!!

CKSyncEngine itself is broken by the same issue. I opened:

FB22309191

Exactly same issue here since iOS26.4. Mac works as expected, on iOS not getting updates on cloud sync. Filed the feedback FB22353668

Wish I'd reported this weeks ago when my iPad showed this symptom on the iOS beta, but I'd assumed it was due to me using a sandbox user since Apple was so bullish in their WWDC 2023 video about the number of test cases they'd created for CkSyncEngine.

I'd also created a feedback before discovering this thread (FB22344526)

Easy to reproduce - the Apple sample app fails. Hoping it gets taken seriously.

I'm experiencing exactly the same issue since upgrading to iOS 26.4 with the same code, and it's also blocking Live Activities updates. I'm also having issues on tvOS 26.4, which uses CKSyncEngine.

We should not be expected to all file feedbacks for Apple to fix a critical bug that should not have shipped in the first place.

CloudKit is opaque and difficult enough to implement and test that there is sometimes no way to know if we are at fault or if it’s some quirk of the system.

Only apple could have caught this bug with certainty and they should be performing a root cause analysis about why it shipped at all. Apple’s own sample app fails. Why is that not an automated test?

I’d like a robust dev environment for this.

• I’m not confident cksyncengine works for sandbox users.
• I’m not confident cksyncengine works in Xcode simulators
• I’m not confident cksyncengine works in development as opposed to production iCloud.

Without this confidence it’s difficult to set-up, difficult to test and difficult reporting bugs.

I am seeing zero CloudKit pushes delivered on iOS 26.4. Filed FB22367981

Thank you all for filing the feedback reports, which do help. If possible, would you please verify with iOS 26.5 beta (23F5043g) to see if the issue goes away, and update the status here? Thanks again!

Best,
——
Ziqiao Chen
 Worldwide Developer Relations.

I just updated my iPhone to 26.5 beta. The syncing is now working on the iPhone. I have Mac, AppleTV and iPhone all running at the same time, and any change to SwiftData on any of the 3 devices immediately updates on the other 2.

I can confirm my App works again (iPad 26.5 beta) .✅

⁇ I cannot confirm the apple example program works as I've run out of devices (and I'm not sure if CkSyncEngine behaves properly with sandbox users or Xcode simulation)

Appears to be working on 26.5 beta

The issue isn't just with CKSyncEngine. I have a custom CloudKit-based syncing setup, which uses CKRecordZoneSubscription to listen and respond to changes in a zone, and the remote notifications aren't working with that either. I filed FB22380044 ... hopefully this can be patched up with a quick update, as it would break so many apps