Require Assessment Grade for Workshop Activity Completion Blocked

In the Workshop activity, even though I have set a "Grade for assessment" and an "Assessment grade to pass," I receive the following error when attempting to require an assessment grade for Activity Completion: "Require grade can't be enabled for Assessment because grading by Assessment is not enabled." 

Shouldn't setting a "grade for assessment" enable "grading by Assessment"? There appears to be no other setting to "enable grading by Assessment."

Setting "Require grade" to "Submission" produces no error, but receiving a submission grade does not necessarily mean that the student fully completed the Workshop activity by assessing their peers' work.

Screen captures posted here: https://moodle.org/mod/forum/discuss.php?d=410282