This article explains how to enable Active Protection if the tray icon is grayed out and the message says "Acronis Active Protection is turned off" when moving the mouse cursor over it:
Active Protection can be enabled either from the tray icon menu or from Acronis True Image main program's interface.
Method 1. Right-click the tray icon and select Turn on Acronis Active Protection:
The blue-colored shield icon indicates that the Active Protection is now on:
Method 2. Alternatively, launch Acronis True Image, click the Active Protection tab, and then click the toggle to enable Acronis Active Protection: