I have found a small BUG in the Questionnaire module (2.8)
When groups are set, you can only select the groups on the Non-respondents tab and not on the View All Responses-tab.
The work around is to select the group on the non-respondents tab first and then get back tot the View All Responses-tab.
Hi Richard -
I checked with the latest version of Moodle 2.8 and questionnaire for 2.8. The group dropdown does appear as expected. Are you sure that groups are enabled for the questionnaire activity?
This can either be done at the course settings - enabling a group mode and selecting "Force group mode". Or by specifically enabling a group mode on the questionnaire activity itself.
mike