Hi,
That's because of how the random system works.
If we were keeping the pagination displayed with the random option activated, each page of the pagination would display random elements of the whole listing. So on page 2, you might find products you had already seen on page 1, etc. And even going through all the pages, you might not see some of the products. To avoid that the solution would be to store the ids of the elements on each page so as to skip them on the other pages and also redisplay them if you come back to the page.
That's actually an improvements we've added in HikaShop 4.4.1 that we've released a few days ago:
www.hikashop.com/support/documentation/5...ashop-changelog.html
The "random" option can now be used together with pagination on products listings.
The "random" and "infinite scroll" options can now be used together on products listings.