Back-end cart page incorrect and errors

-- HikaShop version -- : 2.6.3
-- Joomla version -- : 3.5.1
-- PHP version -- : 5.6.22

Hi,

we've noticed some weird things on our Hikashop back-end cart page, displaying all the carts from customers. Although the products in the carts are correct, the customer names shown with the carts are not correct at all and seem to be completely random. For example the most recent cart shows a customer from years ago (we can verify this with our completed orders, which are still correct).

We don't look at this cart page very often, so we don't exactly know when the problem might have started, but we haven't changed anything as far as we know.

There are also some other strange issues:
- Sometimes a row in the cart table will display an error notice: "Undefined variable: user_id in administrator/components/com_hikashop/views/cart/tmpl/listing.php on line 118 No registration", please see first attached image
- After we've clicked on a cart and return to the main overview of all carts, near the top suddenly a cart belonging to us as Super User has appeared (while we haven't visited or logged in the front end). When we click on this cart all kinds of error notices show, see second attached image

Our webshop still seems to be working correctly as far as we can see, so we're not sure how concerned we should be about this. Any help would be greatly appreciated. Thanks very much in advance!

Ahh alright, thanks, very much looking forward to Hikashop 3!