The bug was fixed and Dorian's quest triggering is entirely based on approval. If you sided with Templars and allied with them, rather than conscripted them, then Dorian would have started off with very low approval. Have you done the other quest where you go round killing off groups of Venatori? Make sure you take him with you to get maximum approval out of it. If you have done so and still not got his quest, then you may have to do another major quest that has a lot of potential approval attached. Do Into the Abyss and recruit the Wardens as Dorian approves of that. If you are not trying to romance him, then so long as you get the personal quest before you leave for the Arbor Wilds you will be okay, so you can do Wicked Eyes as well if you still haven't got enough approval from Into the Abyss.
Solas is pretty much the same. If you went the Templar path it will have lowered his approval considerably, particularly if you ally with them rather than disband and conscript them. To get his approval up you need to make some decisions that he approves of. Sadly, in the case of the Wardens, this will be the opposite choice (banish) to the one that gets Dorian's approval, so you may find you have to choose one or the other but will not get the improved approval of both. However, you can get Solas' approval up by taking him on every journey where there are those artefacts that he likes to activate and also if you side with Solas over what to do with Cole.
I did have a human mage Inquisitor who allied with the Templars and yet still managed to get both Dorian's and Solas' approval up sufficiently to trigger both their personal quests and the relevant Fade sequence with Solas but it did involve a bit of meta gaming to ensure I had Solas with me at the right times to get approval.