Position the cursor between the words SharePoint and Whether in the first paragraph and add a line break, after that press Backspace and you'll see that the new line does not disappear.

Adding new sections between existing paragraphs or after the last paragraph seems to work fine, but if you have to break up an existing paragraph into two paragraphs and then want to turn it back into one you won't be able to.

https://www.screencast.com/t/NAniQ50c2UU9