Hi
What can be the problem when the attachments are not displayed in frontend (tested with PDF and jpeg) ?
In frontend, we have only the label (translated in french) saying to download the attached files.

They seem to be attached in admin.

Can you try using a different template in order to rule out an issue with the overrides?

Hi
Same problem with another template.

File attached in the admin :

www.awesomescreenshot.com/image/2377267/a2908065079dc89ca66a0ce201f11bfc

You need to double check the category's settings.
IF that category is inheriting its settings from another cateogory you need to edit the master category's settings.

Hi
The item on which I tried to add an attachment is in the main category (all his parameters are used by the other categories).
And the attachements are enabled on the item display . But no icon to download the file attached.
So, I think the problem is for ALL the icons, as mentioned in my other post concerning the print and email icons.

You said "The required CSS classes are located in the k2.fonts.css file.
They can be used just like any other icon font in the template's overrides..
eg: <i class="ICON_CLASS"></i>"
But :
- There is no file k2.fonts.css in /components/com_k2/css/ and in /templates/shaper_helix3/css/
- I don't know the procedure to add these icons.
- I'm surprised they are missing in the initial K2 install.

The icon is a part of the template, by default K2 has an icon font file but it will not add any icons in the template apart from replacing images which were already present.

Adding icon fonts elsewhere in the default template would be obtrusive for people who are currently using it.

The stylesheet's path is /media/k2/assets/css/k2.fonts.css
github.com/getk2/k2/blob/master/media/k2/assets/css/k2.fonts.css

An example would be:
<i class="k2icon-arrow-down"></i>

OK . I found the file k2.fonts.css

But what can I do with :
"An example would be: <i class="k2icon-arrow-down"></i> " ?
Where to put this code ?

For ex, if, for each item, I want to display : the icons print and email, the icons links to gallery and video, and the icon download for the attached files.
In this k2.fonts.css, I found :
.k2icon-printer:before{content:"\e02e"}
.k2icon-envelope-letter:before{content:"\e01f"}
.k2icon-cloud-download:before{content:"\e083"}

But, as the template has no specific code for K2 (Helix, from Joomshaper) I think I will not be able to display any of these icons.

You need to override K2's template files (if overrides do not exist)
getk2.org/documentation/tutorials/174-templating-with-k2-and-the-concepts-of-sub-templates

The file you need to edit is item.php.