Hi @perties
Hope you are doing well. Sorry for the delayed response.
The Required Fields of the Review Form are Review Title, Reviewer Email, and Review Summary. If any of them are empty, you will not be able to submit the review. Please check this screenshot for a better understanding.
Since an Error notice is appearing if any of the required fields are missed while submitting the Review Form on my end, maybe there is something wrong on your end. Can you please provide me the link to that review form where you are having an issue? SO that I can check and let you know a solution if there is an issue.
You can also create a ticket at our support center. The link to our support center is included in the description section of the plugin details page.
Looking forward to your response.
Best Regards
Prosenjit