There are numerous reports of Google Maps listings, Google My Business listings that have had their suspension removed then seeing all of the reviews they had on their listings vanish. Joy Hawkins at the Local Search Forums wrote “listings that are suspended and then reinstated are missing all their reviews. This isn’t intended and Google is aware of the issue.”
There are numerous threads about the issue, both in the Local Search Forums and in the Google My Business Help forums.
Ben Fisher in the forums said we should learn from this and document the before and after, so we can show Google the evidence of the previous listing. He wrote:
Another thing to add to this, please please please, document your GMB Profile CID. One thing we are seeing is that on reinstatement a new Profile is being created, the only way you will know this is if your CID or Place ID is different. This is happening in conjunction with the lost reviews.
You should have this handy if you are heading to support and trying to get your reviews back.
Additionally, if you are ending up with a new CID (Profile) you should soon be able to ask Google to revert it back to the previous CID via support.
Forum discussion at Local Search Forums and Google My Business Help forums.