Error on order products by category on backoffice

[yourzed]

Hi, I got two stores with prestashop version 1.7.5. As other versions, under product configuration I have:

Products by page: 16
Order products by: position inside category
Order: Ascending.

When I go to catalog->products. Filter by category, and select one of the categories I have, and also click on the position arrow, it doesn't show the drag&drop option, there is no way to change it.

What I am doing wrong? before it was like this.

 

Thanks in advance

[yourzed]

Error solved. Before moving the products, you have to press a button called (in spanish) "pedir de nuevo". Don't know why, and what it says in english, but in spanish it doesn't make sense.