My experience is that even though Lae'zel was abducted, Yenna disappears as soon as the conversation with Orin happens where she impersonates Lae'zel. I could try going back to the point before Lae'zel was captured and long resting a few times to try and get the scene where Yenna and Lae'zel face off to trigger, but that's 20-30 hours ago in my PT. I filed a bug report hoping Larian brings Yenna back. I just worry Grub will miss her.
