Step to reproduce

• Create a Choice activity with visible groups mode,  Publish results = Always show results to students,  Privacy of results = Publish full results
• Create 2 groups (A and B) and assign a student to each
• Login as student in group A
• Ensure "My Groups > Group A" is selected in the "Visible groups" selector and refresh the page.
• Select an option and click "Save my choice"
• Login as student in group B
• Ensure "My Groups > Group B" is selected in the "Visible groups" selector and refresh the page.
• Select an option and click "Save my choice"
• You should see just your response
• Set the "Visible groups" selector to "All participants" and wait for the page to load
  • Expected: You see responses from both groups
  • Actual: You see the response from group B
• Refresh the page
• You should now see responses from both groups

I believe that this is due to the group selector code being moved in MDL-73438, so that the selected group is being stored after the list of responses has been generated. On the next page load, it is set correctly