Here a list of some issues founded on MIUI after updating and its solutions:
#1 issue: “Reboot to Recovery mode” and “ Choose update package” options gone in Updater on 10.2.28.0
#1 Solution: Click 10 times on the big colored “10” in Updater, you will activate the missing options “
#2 Issue: GPS not accurate after updating to Android 9 (Pie)
#2 Solution: Uninstall last Google Maps update and deactivate auto-update of the app. Google Maps working version is 9.85.2
#3 Issue: After updating to Android 9 (Pie), The fingerprint stops working.
#3 Solution: Restart your phone.
#4 Issue: Battery results show wifi usage active all the time even WiFi is disabled.
#4 Solution: Disable option: “Settings => Additional settings => Privacy => Location => Scanning=> WLAN scanning”
#5 Issue: At Low brightness the screen start flickering, or auto brightness is not working any more.
#5 Solution: install app called OLED Saver as a temporary fix
#6 Issue: In Any Android 9.0 (Pie) version the “Mi Video” app crashes while saving slow motion video.
#6 Solution: Change the language to English just temporary till there is another update.
#10 ISSUE: “No signal” issue while using Bluetooth car interface on Android 9.0 (Pie)
#10 SOLUTION: Simply change your SIM from Slot 1 to Slot 2. [Temporary Fix]