I´ve the same problem, Len appears me in the truck but, she´s don´t recruited
You don't recruit Len that way, you need to complete the hunt in the apartments map then talk to Mason while he's having sex with Mrs. Wayne/Yamada. Keep interacting until he mentions Len, then head to room 101 and she'll be there. Don't know if there's any other prerequisite, but that's how I did it.