Q&A - 503 error when trying to add an Answer from the back-end

(My first attempt using Q&A...)

Logged in as an Editor.
Created a new Question.
Then, in left-side Dashboard menu, clicked to Answers, clicked to Add New (like I did for Question), and it threw a 503 error for this URL: example.com/wp-admin/post-new.php?post_type=answer