by Ken Task.
Could you try:
From command line an inside code/admin/cli directory, issue:
php ./backup.php --courseid=# --destination=[/somedirectoryoutsideofmoodle/]
Where # is the course ID number of one of the troubled courses.
and destination is one that you must create and can access.
Query:
SELECT q.id AS quizid, q.name AS quizname, q.course AS courseid FROM mdl_quiz q;
'SoS', Ken