I accidentally clicked the exit back to Titan’s Canyon after entering the Maj’Elka Waystation. After loading back to Titan’s Canyon, I found the exit to Maj’Elka Waystation blocked and Spymaster Zerrick dead. As the gate normally opens by killing Zerrick, I couldn’t reenter immediately. Using a town portal and returning to the Titan’s Canyon waypoint respawned the boss fight and allowed me to proceed. Here’s a screenshot of the situation in Titan’s Canyon after returning from the Maj’Elka Waystation.
On another note, there’s currently a nonfunctional waypoint at the Maj’Elka Waystation area. It looks like a waypoint and gives the visual activation effect when you go near it but you can’t actually travel to it through the world map. I got fooled by the waypoint and had to make another trip through Titan’s Canyon when I tried to retest the bug.