The "red war circle", in some cases, is set to the zone's center, not the player position, which may cause this, especially in large zones, like the hills or mountain zones:
War starts, player is inside zone but outside the circle, which is far away
Player moves a bit and ends up leaving the contested zone, stopping the war death count
Player keeps fighting, since the enemies are still around, but the war won't end
The "red war circle", in some cases, is set to the zone's center, not the player position, which may cause this, especially in large zones, like the hills or mountain zones: