How many products do you have on each node?

Field value deltas start at 0, which means if your display only has one product attached to it (or you have a single-value product reference field) then you should be using [node:field-product:0:field_product_image] instead of [node:field-product:1:field_product_image].

Poor UI, IMHO - it doesn't provide the 0th value in the available tokens dialog, but it works if you type it in.

For multiple-value image field metatags, there are a couple issues:

First, the Metatag module/submodules currently list all image urls in a comma-delineated list in a single meta tag. There is a fix for Open Graph tags at https://drupal.org/node/1305402#comment-6420040.

Second, selecting which image you want to use from a multiple-value field doesn't seem to be working currently. Same issue, later comment: https://drupal.org/node/1305402#comment-7890015

I'm also working on a sandbox module to expand the Metatag module to provide integration for Drupal Commerce/product-related tags, available at https://drupal.org/sandbox/rvallejo/2102725. I include the fix for splitting multiple images into multiple tags for Open Graph and Twitter, based on code at the first comment I linked to above.