They are not bugs. Google felt that in the car dealer market, most, if not all, the reviews on Google My Business were spammy. So those reviews are filtered. One Google Employee said the following:
“I can’t share with you the specifics of why Google treats most car dealership reviews are spammy. The details of the conversation were under NDA. I assume though that they have looked at a lot and have solid grounds for their understanding of the situation.
The ones that I have looked at appear to be guilty of either the misuse of on-site terminals to gather reviews or the use of third parties to post feedback cards as reviews.”