Hey Drew,
the problem is that a “Preview” in WP renders only the page in question, separately from any other data; in Kanso’s one-page mode the single page is technically not displayed by “glueing” all the comprising pages together, with their respective templates (this would be quite difficult to achieve and rather awkward to maintain in WP), but by using only one page that uses template file – “page_one-page.php”, which in turn queries all the other pages and takes the necessary data. Taking that into account, it would be possible to “Preview” the master page which has the “one-page” template, seeing all other page data included into it.
I am not sure I’ve managed to express it in the most understandable way, so if anything is unclear, please let me know!
Sincerely,
Andrii / Satori Studio