If you have recently installed the easy Google Customer Reviews app then you may see the following error within your Google Merchant Center:
Google Customer Reviews hasn't displayed an opt-in notification to your customers in more than 30 days. Make sure your opt-in integration is correct.
This error message is perfectly normal and will appear if you have just signed up to the Google Customer Reviews program, or, if you are returning to the program after a period of not collecting Google Customer Reviews.
Whilst it can take 3 to 5 days for Google to start to show Customer Reviews activity in the Google Merchant Center, it can take a couple of weeks for the above error message to clear. If you're seeing activity start to come in, this means that the app is working correctly.
Contacting the Google Customer Reviews Support Team
If you are still seeing this error after a few weeks within the Google Merchant Center, we suggest that you contact the Google Customer Reviews support team here: https://support.google.com/merchants/troubleshooter/7210868?hl=en
This will allow you to submit a form with your issue regarding Google Customer Reviews; unfortunately, there is no single dedicated "Google Customer Reviews support email" address.