I had the same problem and found it baffling and frustrating. It actually calls into question the meaningfullness of any "scores" - although luckily none of my students seem to have been bothered by this yet.
I'm still getting used to Moodle. The workshop module is an extremely attractive idea. Unfortunately, other problems with the Workshop module have been more salient.
(We're still having issues with the installation so it's hard to sort out whether or not this particular problem is a user error/misunderstanding, a glitch in Moodle's design, a bug, or an installation problem. . .)