Your browser does not seem to support JavaScript. As a result, your viewing experience will be diminished, and you have been placed in read-only mode.
Please download a browser that supports JavaScript, or enable it if it's disabled (i.e. NoScript).
Joined a friend's session. Proceeded to go to a watchtower to unlock. After reaching the tower, I crashed to main menu. My friend's session stayed online.
In my single player session, I already unlock the towers.