I'm pretty sure this didn't work in 4.0.0 either. I use (or used, in this case) the regex find and replace all the time. I was excited when 4.0.1 came out, and I saw that there was a checkmark for "substitute escaped characters," thinking they had fixed it; and then I cried a little inside when it did nothing of the sort.
It's a little frustrating that it no longer works. For now, I have to open my files in another editor if I need to replace something or swap something around. Oracle, please fix!
**update** I found another post about this; at least they're looking into it: Re: Problem with Regular Expression Search and Replace