Do you have "Allow Bluetooth requests with device locked" enabled? It is under Settings/Google/Account Services/Search Assistant/Voice/ on my phone.Only used Google Assistant occasionally before but now that I own a Bluetooth headset unit(Cardo Freecom4+) for my motorcycle helmet, I have found an issue. When the screen is on, it works flawlessly. The problem comes when I hit the power button to turn my screen off and stick it in my pocket. I've gotten it to work once or twice but for the most part, once the screen is off it just will not respond to any of my "Ok/Hey Google" attempts. I have it set to unlock with voice match as well as having Smart Lock set to keep it unlocked when paired with my Cardo unit but again that only works with the screen on. Say, for example I'm listening to music on Pandora on autoplay and I don't like the song that comes on. I should be able to say "Hey Google, open Pandora" followed by "Hey Pandora, next song", but this doesn't work. I can reach up to the unit on my helmet and feel around for the button that will skip songs, but it's on my right side(sun visor button is in the way on the left) so I have to take my hand off the throttle and fuss around with gloves on trying to find said button. I basically have to pull over and pull my phone out just to turn the screen on. This could be a problem if I ever plan to take a long trip. I'd like to be able to say things like "Hey Google, find me the nearest gas station" without having to pull over and fuss with my phone.