Google Now no longer working on Nexus 5x
Just to let you know you're not alone.

too have exactly the same symptoms on a Nexus 5X running 7.1.1
I've tried:


Leaving the beta program, removing Google App (beta) and installing mainstream Google App
Google App Rejoining the beta program, removing Google App and installing Google App (beta)
Deleting all cache data for Google App
Rebooting the phone.


etc. 

Nothing worked.

However, switching to an alternate Gmail account clears the problem. This account is not in general use and although registered on the phone was not active when the App was updated earlier on today.

I do not want to change the main account as I have a vast network of settings and content in the original, non-functional account.