When working in the Appearance Panel, selecting effects like Fills or anything else often switches to a Typing Field. Most of the time I just click away to close it because I don't need to change the name. But I tried once because I had multiple fills I was using to test different effects. When pressing enter, though, the name of the effect doesn't change (I hit Enter after typing each time).

I'm not sure whether the bug is that the typing field is appearing at all, or that the name isn't changing, but here is a quick capture I took of it: