Hi,
Similar issue here too after update.
I disabled zoom and lightbox on product images months ago (both with custom css and the dedicated woocommerce/theme options), but after 1.70 update the lightbox is back ONLY from the second and third product image (I guess on any image except the featured one).
The worst part is that it badly affects the mobile view, as now the swipe gesture between images is stopped by the lightbox that pops up.
I confirmed this issue also on Atelier demo site (http://swiftideas.com/product/plain-backpack/)
Also the option to disable the lightbox in woocommerce settings does not seem to change anything.
Thanks.