After the version 5.1.1, our theme does not have any auto resize functionality implemented for the Woocomemrce and it uses the original Woocommerce Image size system. That is why you need to set proper thumbnail sizes in the Woocommerce options. For more information:
And for more description:
That being said, It seems that you are using the Woocommerce version 3.3.X. Our theme is not compatible with that version at the moment. Our development team is aware of this case.
A major release will be available in a week or two which will also be compatible with Woocommerce version 3.3.X.
At the moment you will need to downgrade the Woocommerce to version 3.2.6:
Here is the instruction: