I have experienced this as well. took some time to patch up common entry routes at a coastal base that i figured would be attacked, well it never was. I ended up spawning back a indeterminate amount of time later to catch a ride, and noticed the wire was gone. Never did the base come under attack. While it's possible a number of things could have happened (team mates driving through or intentionally destroying it) i have yet to see wire stay up after being built.
While not directly related; wire has limited use even if it were working correctly. it's not physically long and requires multiple sets to be useful, it does not fit well in many places where you would want it (in or around buildings, patching up broken walls, filling small gaps from other defenses). Currently i don't use it at all as it does nothing except eat time and resources.

I build a wire and it disappears the next minute :(