This seems to be a common problem1, 2, 3, 4. Hopefully Larian will implement a fix for it soon.
For completeness' sake, another possible cause is having summons with you while travelling through the portal after the final fight with Ketheric Thorm:
After you fight Thorm the 2nd time, and are about to go into the portal to leave - if you have a summon, Jaheira with a bear familiar for me, it will trigger the NPCs outside the portal when you go through. That breaks Aylin's conversation trigger. If you saved at the portal, you can dismiss before and it fixes it. This just saved my Shadowheart romance. She won't "change" if you don't get Aylin to camp.
source
That being said, apparently there is a fix for those not wanting to go back to an earlier save game to both speak with Nightsong and dismiss all summons before leaving the Mind Flayer Colony.
These steps were posted on Reddit, here (credits to user sgarn):
- Be somewhere other than Rivington Camp and save your game
- Find your Baldur's Gate 3 directory and the
/bin
folder within
- Download the latest version of Norbyte's Script extender WITH CONSOLE
- We are using the console to input our commands - You have the right zip file if it has a .dll and a .json file
- Place both of these files (
.json
AND .dll
) into your BG3 directory
- Start up and run BG3. You will get an error at the launcher, ignore it - we'll fix this at the end
- Load your Save game
- Alt + Tab out of BG3, and you'll find a console window has launched
- Copy and paste u/sgarn 's script contents into this window: https://pastebin.com/raw/253E5L6G
- Return to your BG3 game with Alt + Tab, or by clicking the window
- Travel to Rivington, go to Camp (you will not find them in Elfsong Tavern)
- Speak with Dame Aylin, and progress your quest
- Exit your camp, just to ensure we're not still mid-script here
- Save your game
- Exit BG3
- Return to the BG3 folder and remove the two files you placed from the zip file here, the
.json
and .ddl
files
This will stop the launcher from displaying error warnings
Endstate: You DID talk to the Nighstong! Enjoy not going back dozens of hours =)