When downloading response data for questionnaires, the course groupmode is not taken into account when determining which group(s) a respondent is a member of.

Following patch fixes this issue (for the Moodle 2.6 plugin version; although the 2.7 & 2.8 branches also have the same problem).

diff --git a/questionnaire.class.php b/questionnaire.class.php
index 53a2546..1962a46 100644
— a/questionnaire.class.php
+++ b/questionnaire.class.php
@@ -2788,7 +2788,7 @@ class questionnaire {
// Moodle:
// Determine if the user is a member of a group in this course or not.
$groupname = '';

• if ($this->cm->groupmode > 0) {
  + if (groups_get_activity_groupmode($this->cm, $this->course)) {
  if ($currentgroupid > 0)
  Unknown macro: { $groupname = groups_get_group_name($currentgroupid); }

  else {