Learners progress not being tracked

I have asked for this info. I'm getting the answers second hand, but occasionally I get useful info.

The last agent confirmed they were clicking the Storyline Close button (which should be sending course complete/finish, then exit course). The agent reports that it tells them they can close the window, but doesn't take them to the next chapter in the path. and shows they're stuck at 50% progress for the chapter they just finished.

However, of the agents with issues, it seems to be about 50/50 for those who say they've done the entire course, but it still showing as incomplete (and 50% in the backend) vs those who have done part of it and had to start again instead of resume.