Please tell me more about what browser you are using. I assume you are logged in?
I've never encountered this problem before.
I'm using the latest Firefox (v. 21.0) (on Mac 10.8.4). And yes, I'm logged in: I can see my email address and am able to "log out," and the two kuler sets (both with the same default name) I have made show up in Illustrator CC.
Does the name that you are typing pass the following conditions ?
1. Characters allowed in theme name are : "A-Z a-z 0-9 _ & - space" .
2. Theme name must have atleast three characters.
Yes, I've tried to make a new name, "K2" (without the quotes). It doesn't work. As soon as I hit enter, my K2 returns to the default name, "My Kuler Theme."
Minimum 3 characters are required in a theme name. K2 has only two, so it'll not work,
Ah, OK, I'll try that. -- It WORKS! haha -- I have seen plenty of color theme names with 2 characters, but maybe that was the old (better) non-web kuler.