Has anyone here played the Tyrants of the Moonsea DLC and run into this issue as well?

After the battle at Elventree and the cutscenes companions are removed from my party and I am advised to go inside the inn where another plot conversation takes place. During that conversation the companion Lyressa (not in the party anymore) speaks up, but her dialogue is labeled as "Unknown speaker" without portrait. She announces to she will join me on my next quest, but when the conversation is over, her model fades away and she neither joins my party, nor is she to be found anywhere in the vicinity.

At first I thought it might be related to her dying in the battle before, because when I replayed it, I did notice that at some point her portrait was gone from the party roster and there was a black portrait with the the name "party leader" instead. But when I reloaded and made sure everyone in the party stayed alive and safe until the end, what I described in the paragraph above still happened again.

Ok, never mind.

It turns out that the missing portrait and "Unknown Speaker" bug was just a glitch that happened yesterday but didn't happen anymore today, when I replayed the scene.

Lyressa fading from sight was actually caused by her stealthiness (I had changed her strategy so she would remain stealthy all the time). She was still in the room, waiting to be talked to so she could join me again, she was just invisible to me and therefor not interactive. I found out because on re-entering the room, she would always be there again for a short moment, then fade, just like after the cutscene. So I quickly pressed PAUSE, targeted her while she was still visible and interactive, and my PC was able to initiate the conversation required for letting her join again, even though she became invisible again.

Anyway, problem solved, crisis averted. Phew. :D

Another solution is to just talk to her before you enter the inn. She'll be in the party during the cutscene then. :)