What version are you running?
3.0

What's the URL of the page containing the problem?
.../api/review-requests/####
What steps will reproduce the problem?

Create a review request with no reviewers or groups assigned
Attempt to publish with PUT .../api/review-requests/####/draft/ public=1
Review request stats seems to be aceppting the review request with no reviewers or groups assigned, but it won't get published


What is the expected output? What do you see instead?
It should raise an exception that review request must have a reviewer or group