1) If you've connected your Google account before March 1st, 2021, OR if you receive the error message below, you will need to fully disconnect and re-connect your Google Account and then re-select the GMB page.
To fully disconnect and re-connect your Google Account and then re-select the GMB page:
2) GMB messaging works in only one place: in HL OR the Google My Business dashboard. If you enable GMB chat within HighLevel, you will not see any messages in the Google My Business account.
3) GMB messaging is only available on mobile phones right now, meaning (once enabled) you will only see the "Message" button in mobile search results and within the Google Maps mobile app. Google has not yet rolled Messaging out to desktop.