I just found a strange operation with the modding.
the resources on the air conveyors are not displayed. They are displayed correctly in the stockpiles.
So I tested by putting the icon in the ressources.dds file (data \ bitmaps \ atlases in the installation directory). They seem then correctly air conveyors.
So I guess reading resources.dss comes to overwrite the modded dds file.
Unless I am mistaken about creating the file, can you check if everything is correct or why the resources do not appear.
Thanks in advance.