I completed the instance where you get the kit just fine, and had no bugs talking to the suspect in Lion’s Arch, but Kasparak, the skritt suspect, just…. isn’t there. The aetherblade pirates still spawn there and attack, but there is no skritt suspect standing there. I imagine something similar would happen if I went after the quaggan suspect.
So, to fix it, I heard that you can restart this instance by destroying your kit and getting a new one, but now inspector Kiel just has a conversation about where to find the suspects! I can’t get my kit back and the achievement is now completely impossible to complete. Wonderful.