Ah, I figured out what's going on. I live in Canada and your software is not listed in the Canadian version of their site (https://www.studica.com/ca/en/software/graphics/3D-Modeling-Software.html).

In the top right corner, you can change the country. If I choose US (https://www.studica.com/us/en/software/graphics/3D-Modeling-Software.html), your software shows up. Not sure if I can buy it with my Canadian address in the purchase information though.

Anyway, that's the reason I didn't see it. If it's a mistake on their end, I hope you get it sorted out soon.

-- Cody