I know this is an older thread, but I wanted to share a similar experience with notification issues. After a device failure, I recently upgraded my iPhone13 Pro to an iPhone 17 Pro that came with iOS 26.1. I restored from backup, and everything seemed to be working well. My husband upgraded his iPhone 13 Pro to an iPhone 17 Pro at the same time.
My 12-year-old uses a Libre 3 Plus continuous glucose monitor. The primary Libre app runs on
an Android phone that stays connected to our home WiFi. To receive her high and low glucose alerts, my husband and I use the LibreLinkUp app on our iPhones. Before iOS 26, notifications (banner,
sounds, etc.) worked reliably. After upgrading our phones (running iOS 26.1), although the app was receiving cloud data and seemed to be working fine, we just stopped receiving any notifications. We did not realize these critical notifications weren't occurring until we discovered (by accident) that we had missed a critical low blood glucose alert. Fortunately, we were at home at the time, and the loud alarm on her primary Android device woke us up. Both iPhone 17 Pros remained silent. At first I assumed a setup or connection issue with the Libre apps; however, this has proven not to be the case.
Troubleshooting so far (that hasn’t worked):
+Restarted the iPhone and apps multiple times, restarted WiFi and Bluetooth on the primary device
+Deleted and reinstalled the LibreLinkUp app on the iPhone
+Checked iOS app and global notification settings for LibreLinkUp (Allow Notifications on, banners allowed, sounds enabled, Notification Summary OFF, etc.)
+Reviewed Focus/Do Not Disturb settings to make sure theywere not silencing alerts (LibreLinkUP overrides these settings anyway)
+Removed my child’s LibreLinkUp invitation and set it up again from scratch to completely rebuild the connection
+As a workaround and test for the issue, I also tried a third-party diabetes app (Gluroo) that reads data from LibreLinkUp apps on our iPhones and uses its own alarm thresholds. I do get banner alerts from that app, but I still do not get audible alerts even though sounds are enabled. App FAQs indicate known iOS notification issues. I see that someone in this thread recommends not restoring from iPhone backup (which would be a difficult and lengthy project) but the workaround app was not a part of the backup, and notifications are still not working
properly.
Needless to say, reliable app notifications are extremely important for our family. If anyone has found a configuration or workaround that restores reliable audible notifications for LibreLinkUp (or similar apps) on iOS26.1, I would really appreciate the details. Since notification issues appear to be a well-known bug impacting iOS 18x+, I ask Apple to please take this seriously and post any updates asap. Thank you.