Selected number of subcategories wrong in backoffice product associations - PS 1.5.6

Wrong number of selected subcategories displayed next to category name in the backoffice product associations tab. In some cases, the label with the number of selected children is missing at all, althought some of the children are actually selected.

Prestashop cart empty - no product in cart

A real nightmare - customer adds products to the shopping cart, but the cart does not work. The product mysteriously disappears and there is just the annoying "Your shopping cart is empty" message at the prestashop checkout screen. Sure, the customer is guaranteed to disappear as well.