Some icons not picked in synaptic

[dinojr]

I noticed that when I choose the arc-icon-theme in Gnome-3.20, its actions icons are not picked: here is how it looks

For the previous image, I had selected the "matefaenzadark" icon set as a fallback in index.theme:

[Icon Theme]
Name=Arc
Inherits=matefaenzadark
Comment=Arc Icon theme

If I select matefaenzadark as the icon theme in the gnome-shell "advanced settings" application, I get the following:

[ghost]

index.html? Did you mean index.theme?

[dinojr]

Yes, of course, and sorry for this mistake. Corrected.