Now im not sure this is a bug 

 but its kind of annoying.. 
You have one of your Contacts Names Edited & Colored using the 'Edit Contact' 
Feature of WLM, you apply & all is OK 
Now if you click on 'Edit Nickname' in your Contacts Menu by mistake, your custom Name you just edited gets messed up & you have to start all over again. 
I know, this is being very picky 

 .. but saving all your Plus! Settings, doesn't help to restore custom nicks, yet..