I just setup a new Manjaro Gnome in a Virtual Box VM (manjaro-gnome-22.0.4-230222-linux61.iso).
The extension is already installed, but changing the color setting does not have any effect, beneath logout and login i also tried to reboot.
At the extension website someone posted:
Custom Accent Colors - GNOME Shell Extensions
After the latest update I had to set the shell theme to “Custom-Accent-Colors” again, after that it works as it should, great extension overall.
But I figured out, that there is also no shell theme available in “Optimizations”.
What color did you choose? Note that selecting Default will not have a custom shell theme as it will just use the default blue.
Please see:
Also, we have a custom gnome-shell-maia package that changes the GDM and GNOME Shell theme to Maia. If you want the default blue or any other color, you will need to install gnome-shell instead.