Ahh it's tough. I don't have any wonderful ideas - I think I'm hitting a similar patch and cosleeping has stopped working for us - DS2 just kicks the covers off, grabs my hair and face and blows raspberries when he's supposed to be sleeping

Back to getting up and feeding for me. Joy.

If it helps, hang on to the memory of those two nights when she slept thru. That shows she can do it. For some reason, and as you've said it doesn't seem to be anything you are doing as you are being consistent in your approach, she doesn't do it every night, but she CAN do it. She may do it again. Tomorrow, tonight, in a week, but at some stage it'll happen again. Obviously something is going on right now that you're not aware of that is stopping her from doing it again. But it will happen again.

We just don't know when.