Ugh, yeah, that is really misleading. I can’t tell if they just mean “progress since the last checkpoint” or “progress in the sense of you’re going to be backing up to an earlier point in the storyline so you’ll have to jump ahead to your previous checkpoint if you want to pick up where you’d left off”.
I guess they didn’t expect people to think of the story as discrete levels separated by cutscenes? Which is odd because that’s exactly what it is.
-Tom