Thanks for this wonderful plugin !
I have used the version 0.14 for a while with WordPress 3.4.2 and it was working very well.
I settled another blog in WordPress 3.5.1 and installed WP-Pro-Quiz 0.22 and when I did a new quiz in Matrix scoring mode, it behaves very strangely.
If I put information in Criterion and sorting Elements, when I save, it creates one answer for each.
I tried the version 0.14 and all works perfectly with this one.
I haven't tried others versions.
If you need more explanations, let me know, I could do screen copies if needed