It seems Samsung always finds a way for us to be in touch with each other. Essence of COMMUNITY, may be ..
My Google Voice Assistant had always been giving troubles on lock screen for some time despite the phone being new, in that, on lock screen, for the most part, I would get the message "Can't reach Google at the moment".
But, today, it would just fail to show up in the first place. I would feel the buzz when i say 'OK Google' or 'Hey Google' but nothing happens thereafter. However, when unlocked, it works just fine.
Any help would be appreciated.
Settings || LockScreen and Security || Smart Lock || Voice Match
And set it up to your preference
That doesn't fix the issue I've had this issue since May. The only fix is to remove all Google updates and block autoauto updates. Everytime I updated Google services I lose OK Google in the lockscreen. Very irritating.