I've got the teleport scrolls for each race and activated the teleporters, but the quest isn't marked complete. Is there something else I need to do?

Have you activated all 20 teleporter pads, so all the ones marked on the wold map (when you click on an active teleporter) have a blue flame?

Yes, all of them are activated.

I reloaded a few saves to narrow down when I finished this quest, and check what actually did so.

The quest description (repeating some points from Zandalor's dialog) states where to start looking for the elven scroll, and suggests checking the Cursed Abbey for more information. Reiterating that may be enough for you to figure out how to finish the quest, or you can continue reading the spoiler below.





In my case, picking up the second human teleporter scroll in the Cursed Abbey solved the quest (I already had the first human scroll, and the rest except for the imp scroll, since I had not been to the Dark Forest at that point).

That worked. Thank you.