[Fixed] I found out what was triggering the behaviour.
In Odoo source code we have:
aggregated_move_lines = {}
for move_line in self:
name = move_line.product_id.display_name
description = move_line.move_id.description_picking
if description == name or description == move_line.product_id.name:
description = False
uom = move_line.product_uom_id
line_key = str(move_line.product_id.id) + "_" + name + (description or "") + "uom " + str(uom.id)

So since the name and description was the same, description was not printed despited I change the Qweb view.
So the solution is to modify the source code by means of inherit and modify this .py file