First of all, really sorry for the delayed response. Support crew is on summer vacation thus it causes some delay on replying inquiries.
I left alone and trying to catch up. But, starting from August 15, vocations will be over and this problem will be resolved. Everything will be get back to normal like before. Normally our support-get-back time is within 2 business days.
To show the SKU in the product details page, open the "Flexible VM3 Template" plugin, and enable this parameter: Product Details >> Show Product SKU
SKU should be displayed on product details page, above the price, below the product name.
Regards.
Support