Sorry for the late reply, I had this open in a tab, and apparently buried the tab.
Are you getting a dynamic surround box when this happens? I see what you're describing, and I'm getting the surround box.
It looks like to me that the dynamic surround eats the first enter here, but does not in previous versions. It also does it for Ctrl-Enter (nosplit). I'll take a look at it. Only workaround is to turn off dynamic surround for the moment.