Hi Philip,
because it doesn't work the way we want to, we haven't got a live URL for you to take a look, but it is quite easy to reproduce, hopefully the attached screenshots will help show the issue. Using the default protostar template, in the first screenshot you can see the pink sidebar on the left showing some recent products we viewed before, this works ok (edit: after submitting we see the order of the attachments is mixed up, but the images end with 1, 2, and 3).
If we clean our cache to pretend we're a new user who visits our webshop for the first time, the second screenshot shows what he will see. The sidebar is completely empty as you can also see in the Inspector at the bottom, but it is still showing.
The third screenshot is what we want, for the sidebar to be completely gone when there are no recently viewed products.
In Joomla it is common to hide/display a module position using
if($this->countModules('sidebar')):
and this works fine for other modules, but not for the Hikashop Content Module. The countModules function will always return 1 with a Hikashop Content Module, even when it doesn't output anything (except some whitespace), as in our second screenshot.
Hopefully this will help to make it more clear, thanks!