Why Do I Have To Open My Phone To Use Google Assistant?

Selecting the personal results option will enable more capabilities when the phone is locked. But, some things you just can't do with the phone locked. These are Google's restrictions, not Garmin's.

For example, I can't set my thermostat with the phone locked, but I can send text messages and make phone calls. It doesn't make sense to me but that's how it is. 

I selected the personal results options, but it didn't change anything for me. I literally can't do anything without opening up the phone and clicking on the notification.

I can ask the assistant questions with my phone locked but I can't make a call or send a text. It responds with the "first you'll have to unlock your device" message.

Check these settings on your device.

Check these settings on your device. There's one for sending messages. 

I had the lock screen settings enabled but not "on headphones" in personal results. I enabled it and now calls and texts work. Thanks for the help.

Thanks for trying to help, but unfortunately it's still not working for me. Maybe once I get the Android 12 update it will magically start working.

I have the exactly same problem here. Voice assistant works like a charm when lock screen is unlocked, but when lock screen is locked or phone screen turned off, I can't do a thing with watch.

The watch apparently can connect to the voice assistant service since the notification pops up on the phone about the headphones but nothing happens when I try to speak. It is kind of frustrating since I don't keep my phone screen turned on and unlocked all the time (who does that anyway) and makes the use of watch voice assistant feature obsolete.

I think Google is messing around and breaking stuff, as usual. Mine worked for a while and now, suddenly, I have to unlock my phone to make a call using Assistant. Kind of makes Assistant useless for me. If I have to reach for my phone, I don't really need Assistant to place the call for me.

I have a few threads about assistant as well. When I ask to read my messages it will say "something went wrong" - UNLESS the phone screen is on. Then it works.. BUT if there are no messages then when it says "there aren't any messages" - the volume is so low that you can't hear it say that. But the if there are messages - you can hear the texts being read through the watch. I have the same issue with a set of headphones in my ski helmet but then my other BT headphones work fine so it it would indeed appear to be a Google issue. I did open a post on the Google Assistant forum but have had no luck there.