Variation problem

Hi!
Thanks for the plugin.
I’ve read the other threads here since I’ve encountered a problem with variation products.
I have file upload activated on the product page, and guided by the other threads I’ve removed line 9-11 in the plugin product-detail-page.php.
That made the plugin work fine on for example this page:
https://vaxjoprint.se/produkt/fine-art/
But as soon as you start choosing a variation from one of the select boxes here:
https://vaxjoprint.se/produkt/canvas/ the upload button gets disabled. And it doesn’t help to actually choose a variation by making a selection in both select boxes.

I’m puzzled, and hoping you can help.

The page I need help with: [log in to see the link]