WhatsApp for Xiaomi Redmi 3 Pro

MIUI's aggressive battery saver restricts WhatsApp's background process, so the heads-up call banner gets suppressed even while the call rings. Go to Settings > Apps > Manage apps > WhatsApp, open Battery saver and set it to No restrictions, then enable Autostart on the same app page. Finally, in Settings > Apps > Manage apps > WhatsApp > Notifications, make sure Floating notifications and Lock screen notifications are turned on so incoming calls pop up properly. See how others solved this on Reddit

This happens when MIUI restricts WhatsApp from running in the background, so notifications only sync the moment you launch the app. Open Settings > Apps > Manage apps > WhatsApp, enable Autostart, and set Battery saver to No restrictions. Also lock WhatsApp in the Recents/multitasking screen by swiping down on its card (or long-pressing it) and tapping the padlock icon so MIUI stops closing it. See how others solved this on Reddit

First confirm notifications are enabled in Settings > Apps > Manage apps > WhatsApp > Notifications, and make sure the Messages and Calls categories are toggled on with sound. Then check that WhatsApp is set to No restrictions in MIUI's battery list under Settings > Battery & performance > App battery saver, and that Autostart is enabled for WhatsApp. If it still fails, force stop WhatsApp and reopen it so the background connection re-registers. See how others solved this on Reddit

MIUI is freezing WhatsApp's connection in the background, so messages only arrive when you reopen it. Enable Autostart for WhatsApp in Settings > Apps > Permissions > Autostart, and set its battery profile to No restrictions under Settings > Apps > Manage apps > WhatsApp > Battery saver. Also exclude WhatsApp from any aggressive cleanup in the Security app and lock it in the Recents screen so the system keeps it running. See how others solved this on Reddit

MIUI updates often reset Autostart and battery permissions, which silences WhatsApp again. After updating, re-enable Autostart in Settings > Apps > Permissions > Autostart and set Battery saver to No restrictions for WhatsApp under Settings > Apps > Manage apps. If notifications are still missing, clear only WhatsApp's cache via Settings > Apps > Manage apps > WhatsApp > Clear data > Clear cache (this does not delete chats), then reboot the phone. See how others solved this on Reddit

Delayed notifications on MIUI are usually caused by overlapping power-saving features that throttle the app. Turn off the system-wide Battery saver and set WhatsApp to No restrictions in Settings > Battery & performance > App battery saver, then make sure the notification dot and sound are enabled per-category in Settings > Apps > Manage apps > WhatsApp > Notifications. Also check that Do Not Disturb (and any scheduled DND) in Settings > Sound & vibration is off, since it can hold notifications back silently. See how others solved this on Reddit