sync - Gmail app not displaying status bar notifications
Summing up results from the in-comment-discussion: Starting with Android 4.1, notifications can be disabled on a per-app basis: Either by long-pressing a specific notification in the notification area, and navigating from there to the app which sent it -- or directly from the Android settings in Apps → Manage Apps, and selecting the app you want to disable notifications for: here you will Fix - Can't Pull Down Notification Bar in Android Phone Jan 18, 2018 Yahoo Mail Notification Is Disabled on an Android | Synonym
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