I just installed joomla158+VM (ecommerce bundle) and have the same issue.
I think it has to do with "categories" as I installed 2 fresh versions (one with sample data and one empty).
On the empty one
1) created a category
2) created a product and, no matter what I try, it does not show the product details
On the "sample data"
1) created a category
2) created a product and, no matter what I try, it does not show the product details
So, for now it's the same BUT, if I change the product's category to one of the "sample categories", i.e. "Ipod", it works PERFECTLY.
Also:
1) the breadcrumbs are not working fine, and looks like it's a problem related to the first one, as it works with articles, but not with products
2) the sample data categories have an empty flypage also, so I guess it's not the reason
3) any templated resulted in the same behaviour, so looks not related to a template.
I do not know how to solve it, but I guess it will add some light to the gurus.
Thanks!!!