After this last update my offline OK Google Now has stopped responding. It will bring the screen up but it is like it went deaf!! Just sits there until it times out.
A few folks reported this on other forums also. There are a few ways to get to the OK Google settings, so here is one way:
Settings > Accounts > Google Account > Search > Voice > OK Google Now Detection. Make sure "From Any Screen" and "From Lock Screen" are unchecked. The only thing checked should be From Google Search. Hope that helps.