I've created a new Quiz using existing questions from ICMA Learning about eAssessment.

Don't know if you need to recreate it.

Then I ran it with three students.

Then I selected 'No' for Show/Download marks for each question

And got the following error. I also saw the error when doing the same with the existing quiz 'A demonstration of a 'CMA style' formative assessment'.

ERROR: column "qsgrade12" does not exist

SELECT ''||u.id||'#'||COALESCE(qa.attempt, '0') AS uniqueid, (CASE WHEN qa.sumgrades = (SELECT MAX(qa2.sumgrades) FROM dev_quiz_attempts qa2 WHERE qa2.quiz = qa.quiz AND qa2.userid = qa.userid) AND qa.timestart = (SELECT MIN(qa3.timestart) FROM dev_quiz_attempts qa3 WHERE qa3.quiz = qa.quiz AND qa3.userid = qa.userid AND qa3.sumgrades = qa.sumgrades) THEN 1 ELSE 0 END) AS gradedattempt, qa.uniqueid AS attemptuniqueid, qa.id AS attempt, u.id AS userid, u.idnumber, u.firstname, u.lastname, u.picture, u.imagealt, qa.sumgrades, qa.timefinish, qa.timestart, qa.timefinish - qa.timestart AS duration , COALESCE((SELECT MAX(qqr.regraded) FROM dev_quiz_question_regrade qqr WHERE qqr.attemptid = qa.uniqueid),-1) AS regraded FROM dev_user u LEFT JOIN dev_quiz_attempts qa ON qa.userid = u.id AND qa.quiz = 129 WHERE qa.id IS NOT NULL AND qa.preview = 0 ORDER BY qsgrade12 ASC, uniqueid ASC
? line 796 of lib/dmllib.php: call to debugging()
? line 1088 of lib/dmllib.php: call to get_recordset_sql()
? line 1221 of lib/tablelib.php: call to get_records_sql()
? line 288 of mod/quiz/report/overview/overview_table.php: call to table_sql->query_db()
? line 1241 of lib/tablelib.php: call to quiz_report_overview_table->query_db()
? line 399 of mod/quiz/report/overview/report.php: call to table_sql->out()
? line 94 of mod/quiz/report.php: call to quiz_overview_report->display()