I realized that neither highlight-indentation nor highlight-indent-guides works with emacs in server/client mode.
I'm launching emacs server/client like this :
$ /usr/bin/emacs --daemon $ emacsclient -c
I'm launching emacs standalone like this :
I can see that the faces are different and highlighting indentation won't be displayed with emacs client.
The screenshot shows client mode on the left and standalone mode on the right. I disabled every customization to debug.
I use emacs 26.1
Is there a bug to track down ? Do I miss a setup ?