Cannot get the Void Shadows quest to start

I'm on Chapter 4. Got the DLC to start just fine, along with the side quests, etc. Reached the end of 'Aberration's Lair', and since then have been jumping from system to system, but nothing happens. Done the Haunting, Card Inverted, fight with a random transport protected by two heretic ships, etc. Lots of side stuff, but the next main quest just refuses to start despite my jumping around about 40 times. What gives?