I would love to be able to add blank lines anywhere via the WYSIWYG editor and have them persist as part of the document. Documents feel "cramped" to me if I'm not able to add the occasional blank line. I understand that blank lines aren't exactly supported by markdown so this would likely be a WYSIWYG-only feature, and that's fine. I am able to add blank lines in the markdown with "<br>" but oddly, these disappear after switching between code/markdown and WYSIWYG modes.
I'm currently using pre-release version 1.2.4 on Mac. Also using that version on windows.
PS - other than the inability to create spaces, I'm very happy with the WYSIWYG editor so far. I'm not keen on editing markdown and then seeing a static rendering, I love being able to make inline changes in the WYSIWYG editor. I'm using Joplin as a replacement for OneNote and it's fantastic!