Come across some very weird bug which is causing a silent dying in get_records_sql() ~370 of accesslib.php

I discovered some problem with choice answers not appearing and reproduced it by:

1/ create blank course as admin user
2/ admin user creating a choice
3/ admin user answers choice
4/ view choice responses - get nothing
5/ add admin user as teacher to choice
6/ try to view responses

php is silently dying somwhere (despite full dev debugging). Working through trying to discover where its dying it seems to be in get_records_sql!

echoed query out:

SELECT u.id FROM user u
INNER JOIN role_assignments ra ON ra.userid = u.id
INNER JOIN role r ON r.id = ra.roleid
LEFT OUTER JOIN user_lastaccess ul ON (ul.userid = u.id ) WHERE ra.contextid IN (73220,73210,61,1)
AND u.deleted = 0
AND ra.roleid in (41,31,21,11)

ORDER BY u.id ASC