At our agency, we also use Local Viking. Recently, I’ve been receiving email notifications stating that we are losing dozens of reviews. However, many of those reviews are not being fetched through the API, even though they are still visible and live on the actual Google Business Profiles.
I agree with the comment above, Local Viking does not provide a direct link to the reviewer’s profile. To verify, I copied the reviewer’s name and used Gmail’s advanced search to locate the original notification email. When I checked the profile manually, the review was still publicly visible on the GBP. And yes there are some reviews which are actually disappearing but not as many as Local Viking send the notification.
In our case, we manage nearly 80 GBPs under a single Local Viking account. Each profile has between 450 and 1,500 reviews, and all of the businesses operate in the home services industry.