In case it's not intentional, In act 2, Lyx's Heart hint says that you must be in act 3 to continue, not that it's NYI, but as far as I can tell, she's not in act 3 yet? And, once you enter act 3, it changes to say it's NYI
It's intentional - at that point you can't progress until you hit the next act. And she's not in Act Three right now, hence "no more content in this version". This will of course be changed once she's re-introduced :)