Very Confuse about content module

-- url of the page with the problem -- : ccfia.org.tw/xmas2/index.php/shop/candle
-- HikaShop version -- : HikaShop Business 2.6.3,
-- Joomla version -- : 3.51
-- PHP version -- : 5.5.12

Hi,
I use content module for the category menu, as showing in ：
The URL is ccfia.org.tw/xmas2/index.php/shop/candle , and the category menu is one the left,
and in my sample data, the category has only one level,
Following are my questions:
1. Since the category has only one level, the triangle icon on the right shouldn't be showed up.
2. When I clicked on the triangle icon, it shows : No subcategories, (ContentModule2.png)
3. When I click on the item name, it lead to the correct product list page, but the category disappear, to make it simple, I actually set the "menu assignment " to all pages, but in the product list page, the category menu still missing.(ContentModule2.png)
4. In socks product list, I enter the green sock (the first one) page, I can see the category menu
but if I enter the gray sock (the second one) page, I can not see the category menu, but these two product's seeing is 100% identical, (sock1.png, sock2.png)
5. Though some product detail shows the category menu, but when enter, the menu expand, so still sees the "No subcategories", (sock1.png)

I might missing something, please help
Best Regards