PHP 7.1, MySQL on Ubuntu 17.04, ZC 1.5.5.e fresh install, no plugins.

A quick question, I seem to be overlooking something, or doing something really wrong. Like the subject says: a fresh install throws an error at me, whenever in a newly created category, I try to make a product of the type document_general. Preview works, but after several fresh installs, it just won't create the product. I repaired it in the file YOUR_ADMIN/include/modules/document_general/collect_info.php at line 303 by inserting:
Code:
echo zen_draw_hidden_field('products_quantity_mixed','0') .
       zen_draw_hidden_field('products_qty_box_status', '1') .
       zen_draw_hidden_field('products_quantity_order_max', 1);
I don't like this solution, but at the moment I can go on with other work, and wait for comments of a ZEN guru