A further test suggests that the editor in Pending behaves somewhat differently than in Reply or New Topic (where I tested before).
2. Likewise, DELETE+CONTROL+RETURN ... does accomplish the intendedIn Pending I have the same result. But interestingly I also get that same result with a plain Enter (no shift or control). Is that the same for you?
1. I confirmed that using DELETE+SHIFT+RETURN ... does NOT doIn my test the Delete had the expected effect (joining the two paragraphs) but Shift+Enter broke the line back into two paragraphs, rather than inserting just a line break.
I am using Firefox, Windows 10 and Office 365 v. 174 on a LenovoI'm also using Firefox, on both WinXP and Win10 desktops.
As to the difference between the behavior of this editor versus a word processor such as Word, I think it is normal in an email editor for Enter to insert a line break rather than a paragraph break. I have never used Outlook, but that is my experience with Gmail, Yahoo Mail, Thunderbird, Eudora, and others.
That being the case, using Shift to modify the behavior is consistent with convention.