After my Surface Pro 3 tablet installed the Windows 10 Anniversary Update, the Action Center tray icon was missing from taskbar and I could not get quick access to common system settings and app notifications. Other system icons such as the Network, Power, Speaker icons were also gone. I opened the Notification area of Taskbar, and the corresponding toggle became grayed out.
Once the action center button and other system icon are not present on the right side of the taskbar clock, it may be hidden. You can right-click on an empty space in the taskbar, go to Settings > Personalization > Taskbar, click Turn system icons on or off, and set the Action Center to ON. If not, you could try any of the method to resolve the problem.
How to fix Action Center Taskbar missing and grayed out in Windows 10 Setting
* Open Control Panel, go to Hardware and Sound > Device Manager. Or you can right click on Start menu and select Device Manager.
* Double click on Batteries selection to expand all items. Find the Microsoft AC Adapter item and right click on it, and choose the Uninstall option.
* Then right-click the top one from lists, and select the “Scan for hardware changes“ to check if all System icons icon come back in the Taskbar Notification Area (Systray).
If it is still not working, you may need to make change with regedit editor.
* Tap or click on Start button, type regedit to searching box, and select it from results.
* Navigate to the location in the left pane of registry editor:
HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\ MicrosoftWindows\CurrentVersion\TrayNotify
* In its right side pane, there are two strings named “iconstreams” and “PastIconStream“. Right click the iconstreams to delete it and do the same way with another.
* Finally restart the system to apply all changes.