The workaround is to run past the first group of Tal Shiar that are walking down the path towards you, and keep running until you reach the first campsite. You may want to put your BOFFs into passive mode so they don't accidentally kill any of them. Once you reach the campsite, the objective triggers, and you are able to kill the first mob. If you kill even one of them before the objective has triggered, you will not be able to complete the mission.
This character is why I don't play my Romulan any more. Tovan Khev is NOT my BFF! Get him off my bridge!