Hi! I found this thing:
I have the navigation menu set up in the "default" text format, but when I make changes in the text formats panel it doesn't update the navigation menu automatically, and it changes the style, going from "default" to "--SELECT--" in the "customize" page.
This happens the most with the text color, I have a dark background website so I gave the default text format a #eee color, but when I change anything the navigation menu text becomes black.
I hope I'm clear enough! and if this isn't a bug please let me know what I'm doing wrong!