Activity (duration) being tracked by LMS

My LMS launches content in a new window by default. The LMS guys are saying that Storyline content continues to send evidence of the content being active from that new window if a learner walks away and doesn't close the window. We now have a learner who has spent 57 hours on a module. ;-)

The LMS will log the person out after 15 minutes of inactivity on the system, but the content window stays open if it has not been closed manually and it seems that the time taken continues to be counted, which seems bizarre to me. I would have thought the content window should also be able to detect inactivity after 15 minutes and stop sending tracking information.

Any advice from more techie people on how I can get resolution on this? They say it's to do with the way Storyline content is communicating with the LMS.