Issue with tracking completion

We recently launched an eLearning and I'm having a handful of people coming forward saying that the course isn't tracking their learning as complete, despite completing the training. When they go to resume the course it takes them back several slides and they are unable to move forward.  Also - in some of these cases, I do go into the learners profile and the learners are in fact showing as complete.    I currently have the triggers set up on the last slide to show the course as completed when the timeline begins on the last slide but also have a trigger to exit the course when they select an exit button on the screen.  Any thoughts on as to why this might be happening or what I can look into to trouble shoot?