That was not the reason you described. In current puzzle app is size of pieces hardcoded as an constant (not equal to zero ). You can still scale generated puzzle in easel manually after import (do not forget to select all pieces to prevent different sizes). It is not much comfortable, I know. I am preparing new version with many improvements, so stay tuned .
The problem that app did not work on some browsers was missing end of svg tag. It seems that chrome fixed it, so I did not discovered the problem before. Sorry for that, I will do my best to avoid such errors in future and test the code in more browsers.
So the issue should be fixed now. Please, let me known if there are still some issues, especially in explorer, because I do not have chance to test it.