Many iPhone 6s/7/8 and iPhone X users even on iOS 11 are facing the issue that notification that pop up at lock screen are missing in apps after unlocked and checked the iphone. Like in case text message app a user’s receives the message notification on lock screen but as soon as he unlock his iPhone there are no new messages in the iPhone. The message is not showing in notification center again. The banner notification stays on lock screen approximately 5-10 minutes and then disappears making it appear that there were no texts. The issue can happen with any app notification like email, message etc on any iphone model. A user with only one week old iPhone 8+ on iOS 11 is facing issue with lost text message after unlocking the phone.
it's really annoying, the message disappearing from iPhone is not consistent - definitely intermittent. Some message notifications appear fine, others don’t. For many users this all started with iOS 11. User loses the notifications and the messages they represented. There is an observation made that It happens for any message from anyone received when iphone is turned off.Even on the latest iOS beta 11.3 the message are disappearing from iphone. Moreover the issue is independent of any network like Verizon, AT&T etc. Surely this is bug from Apple.
The Apple support staff are informed by many iPhone users and it seems that the matter is escalated to engineer. Apple should work on this and fix this issue in upcoming release as the issue is not small and user may miss an important message.
Fix 1: Toggle "Show in History" off
One working solution found for this is to toggle “show in history” setting to off . Settings > Notifications > Messages > Toggle "Show in History" off
Fix 2: Reset Your iPhone
This is a temporary fix for the text message disappearing from iPhone but works for few days. Just reset you iphone from setting and see if it helps much.