I went to export grades to excel. After the settings screen appears, I click "Download" and the headings appear, but not the student names & grades. This is the error message:

Debug info: Unknown column 'rainner.userid' in 'on clause'
SELECT g.* , u.lastname AS usrt1, u.firstname AS usrt2, u.id AS usrt
FROM mdl_grade_grades g
JOIN mdl_user u ON g.userid = u.id
JOIN (SELECT DISTINCT eu1_u.id
FROM mdl_user eu1_u
JOIN mdl_user_enrolments eu1_ue ON eu1_ue.userid = eu1_u.id
JOIN mdl_enrol eu1_e ON (eu1_e.id = eu1_ue.enrolid AND eu1_e.courseid = ?)
WHERE eu1_u.deleted = 0 AND eu1_u.id <> ?) je ON je.id = u.id

JOIN (
SELECT DISTINCT ra.userid
FROM mdl_role_assignments ra
WHERE ra.roleid IN (?,?)
AND ra.contextid IN (168,3,1)
) rainnner ON rainner.userid = u.id
WHERE u.deleted = 0
AND g.itemid IN (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)

ORDER BY usrt1 ASC, usrt2 ASC, usrt ASC, g.itemid ASC
[array (
0 => '4',
1 => '1',
2 => '3',
3 => '5',
4 => 40,
5 => 44,
6 => 46,
7 => 50,
8 => 51,
9 => 55,
10 => 56,
11 => 63,
12 => 67,
13 => 72,
14 => 76,
15 => 77,
16 => 80,
17 => 81,
18 => 87,
19 => 88,
20 => 93,
21 => 97,
22 => 101,
23 => 102,
24 => 106,
25 => 107,
26 => 108,
27 => 109,
28 => 12,
)]
Stack trace:
line 391 of \lib\dml\moodle_database.php: dml_read_exception thrown
line 749 of \lib\dml\mysqli_native_moodle_database.php: call to moodle_database->query_end()
line 166 of \grade\lib.php: call to mysqli_native_moodle_database->get_recordset_sql()
line 225 of \grade\export\lib.php: call to graded_users_iterator->init()
line 59 of \grade\export\xls\index.php: call to grade_export->display_preview()