It only worked for me for Google Home and Google Mini...and over the weekend it stopped working for those devices, also. It never worked for my non-Google devices, nor for my phone. I found it to be very useful when it is working.
When I say "Ok Google" I have to give it a command within a few seconds.
If I don't give a command soon enough, I have to say "Ok Google" and give a command all over again.
After saying "Ok Google" it doesn't just sit there and wait indefinitely.