In some firmware for use GG, you need to allow the use of floating windows. Sometimes it is called the notification, alert, docking area, dropzone and so on.
MIUI v5: Go to Settings - Applications - everything. 2. Find Game Guardian 3. Enable slider "Pop-ups"
Screenshot
https://www.youtube.com/watch?v=0Xxj7Kz7WjQ
MIUI v6 / Flyme: Go to "Settings" - "All Applications" - "All" found "GameGuardian", in its turn slider settings "pop-ups".
https://www.youtube.com/watch?v=hZfcIT74PS8 Sometimes Flyme meets mistranslation as the Alarm (second paragraph):
MIUI v7: Go to the application "Security" - permission - permission - GameGuardian - Pop-up windows.
EMUI: Phone Manager - Go to Settings (Settings) - Shortcuts - looking there dropzone manager - activate it. Now its icon available on the desktop. We go to the dropzone manager in the list of GG and allow access.
The popup does not show on Huawei phones by default. You will need to allow GameGuardian to show popup. Please open the Phone Manager, then Dropzone Management and please make sure it is turned on for GameGuardian .
The Popup also does not show on some Xiaomi phones. You need to head to Settings -> Installed apps -> GameGuardian -> Other permissions -> Display pop-up window.
Also, other phones may have different procedures to allow apps to show Popup windows. All such apps are usually affected this way, for example the Google Translator app with the Tap To Translate functionality. Therefore, you can simply google "YOUR_PHONE tap to translate" to find the solution. For example, for Xiaomi Redmi devices the solution is as follows: https://productforums.google.com/forum/#!topic/translate/1Pywh5vI1kE