I recently updated to the new CM 12.1 nightly on my Oneplus One from the official version because of constant touchscreen issues. The touchscreen issues are now fixed, but OK Google doesn't work from the lock screen any more. I also can't select it from the Google Now voice options or through settings>language and input. The device is rooted. I've googled this issue a lot, yet no one else seems to be having this issue. I also know a lot of people don't rate OK Google, however I'd love to have the functionality as I recently got a Bluetooth stereo for my car.
Anyway. would be great if anyone had an idea. Cheers!