Yeah, the last update killed it, frustrating. It was working pretty well, for a long time too, kind of got used to being able to use it...
I get all notifications (from Android Cortana) except messages, to clarify. The option to sync messages is "greyed out" now on my device too, and if you check the KB, it says the PC needs to be an AU build (hmm, yeah...) to enable.
Oh, and occasionally I still get messages, but I can't reply, they just pop up, maybe every 20th or so, it's odd.
Something is clearly very broken, again.