In "Plan my book with me", pressing Enter in "It must include" does not make a new line. How do I add a line?

This is fixed in version 1.9.21. In every "one per line" field of "Plan my book with me" (It must include, It leaves out, Never in this book, the facts, terms, characters and places), Enter now starts a new line exactly where your cursor is, and the cursor stays there, so you can insert a line between two others. Before, the empty line vanished and the cursor jumped to the end of the field. Blank lines and extra spaces are tidied up when you leave the field.