Hello Dominic,
Thanks for reaching out with a detailed description and a screenshot! I understand that the quiz score and "Take again" button do not show up for some of your students.
This is strange, especially when you cannot replicate it on your tests. I'd start by checking whether your students are using an updated version of a supported browser. Regarding the lesson not being marked as complete in your LMS, try using SCORM 2004 4th Edition and Passed/Incomplete or Passed/Failed as your publishing options and see if it helps.
If these don't improve things, could I have you connect with us in a case so we can dig deeper into the issue? We might ask you to enable debug mode in your course so we can review communication between the course and your LMS.
