The radio plugin configuration saves the setting of the "Show the All Channels group" option to the "showallchannelsgroup" entry in MediaPortal.xml, but the radio plugin reads the "hideallchannelsgroup" entry (which is identical with the tv client setting and is not changeable in the radio plugin's config). So the setting in the radio plugin's configuration is always ignored.

h4. Steps to Reproduce
Change "Show the All Channels group" and see if the radio plugin respects this setting.
I made the experience that I could not hide the All Channelds group on a fresh install. But you might have to try both ways (hide and show) depending on the state of the tv clients's setting.