I got the exact same bug as described in this topic with a fresh created character:
https://forum.lastepoch.com/t/void-assault-bug/45033
Here is the log file from this session: (After arriving I ran over the map to see if I forgot something, but couldn’t find anything)
Player.log (251.8 KB)
Short: When arriving at the target location, nothing happens. I tried to include a screenshot, but no picture file format is allowed. 
I did nothing special. I lunged to an enemy that was at the edge of the screen within the target area and nothing happened event-wise. It was quite a long distance lunge, since I have a 21:9 resolution (3440 x 1440) and the enemy was at the edge of the screen. Other than that I have no idea what could break this quest. Especially since I already completed this part of the quest with another character today.
Edit: After going back to character select, entering again and fighting to the area it worked. This time without lunge.