Why did norton 360 not find "TR/Crypt.XPACK.Gen"?

Why Norton 360 did not identify and remove "TR/Crypt.XPACK.Gen"?

I ran "Restoro" which identified  "TR/Crypt.XPACK.Gen" and removed this file

Windows 10 PC

TR/Crypt.XPACK.Gen is the generic name for threats detected by Avira and categorized as unknown Trojans. Typically, these programs are designed to steal personal details or spread other malicious programs such as ransomware.

One of the purposes of this particular Trojan is to monitor victims' browsing (internet) activities. If Trojans are installed on your system, eliminate them immediately.