Your response contain errors which are highlighted in red. Please correct them and try again.

Hi folks, I`ve configured a mandatory 10 question quiz for testing purposes. The Quiz seems to work fine, until I omit answering a question. An alert "Your response contain errors which are highlighted in red. Please correct them and try again" is generated and expected - however the question that was omitted is not highlighted in red? Am I missing something? Thank you in advance.