Ok, I have a confirmed solution for you guys. @fuuz
Since i ran into exactly this problem yesterday.
Make sure you have the assistant installed. and go to your Play Store and search “Google” And open the page for the Google, app. The actual google app.
this one.
And uninstall it. It won’t remove it. It’ll just uninstall the updates. Then on your watch/phone. Go into the Google, app. The one just marked as Google.
Make your way into the settings and enable the Ok Google settings. It will likely look a bit different than the newer versions. It was in the Voice settings for my phone, and i forgot where it was on my kospet hope.
Then go into your Google Assistant and go through it’s internal set up. If it asks you to update your Google app. That’s fine. Go ahead. go to the play store and update it. Just remember to enable the Ok Google settings on the older version first.
Now your google assistant should respond normally.
Here’s the catch. Do NOT go into your Google app settings where you would enable the Access on Voice Match. We’re grandfathering in the settings from the older version.
Edit: Sometimes when the Google app updates it breaks it again. Just noticed. It’s pretty hit’n’miss.
For my kospet hope, updating the Google app breaks it. But the default version is fully featured anyways. Soo… Just be sure to grab the offline voice recognition packs and such. 
I’d give a video tutorial. But OMG that would be a PITA.
How i discovered this fix. I some how broke my assistant last night while looking at my settings just trying to figure out how to get it to work on a phone. And this was how i managed to fix it. I also got Google Assistant working on a phone that doesn’t even support Google Assistant. So you MAY be able to side load it onto a Hope Lite (install with APK), and get it working with this method.