Board Thread:Support Requests - Getting Started/@comment-28687587-20170615235622/@comment-168424-20170617160133

It looks like you always get put into the Classic RTE creating a new page unless you have the Source Editor set as preferred.

You can ask Fandom staff at Special:Contact/general why you can't get the VisualEditor for new pages.

FYI, what you call "Preview Mode" is called the VisualEditor. As I said above, the Classic RTE actual is a "preview mode" editor also.