correct, in the address book you ONLY use their nickname, NOTHING else. When you turn the REMOTE OFF, even if you have a script loaded, this will disable it. let me ask this, was your mirc a clean instal? Did you get it from mirc's official download page
or someplace else? If you downloaded it from mirc's official site, it's a clean instal, you've turned the address book on, are using the nickname proplery, then Im out of ideas of how to further guide you except to tell you to completely reinstall mirc.
I currently have 13 different settings (4 user levels, 2 idle timers, any nick Im using, opped, voiced, and on the 4 mirc internal user lists (auto op, auto voice, protect and ignore) in my nick colors and they all work fine.
let's try an experiment ok?
1) OUTSIDE of all channel, Erase EVERYTHING in the Nick Colors section of the address book.
2) Open the address book (ALT + B), go to Nick Colors, click Add
3) Pick a color you like
4) For Method, use "Message and Listbox"
5) check "Nick or Address"
6) in the field below, type your primary nickname
7) leave EVERYTHING else untouched
8) join a channel and see if your nickname is the color you chose
9) change your nickname to anything else and see if your nickname changes color (it should if your primary nickname is the only one on the list).
10) Report back here with your results.