Gallery images didn’t work

Hi! first of all thank you so much for this amazing plugin.

Since the last update (3.0) the product gallery doesn’t work, before the update the product gallery images were shown in a small thumbnail and when you clicked the thumbnail a window opens and you can see the bigger image. Now the images are showing in the default size and there’s no option to see the bigger image.

I need to update something else to fix this problem? This really mess up my theme’s design.

Thank you so much for your help!