Scott,
I realize it has been nearly a year since your post, but I ran across the same behavior while trying to publish the Story Map Tour today. This type of error is sometimes resolved by clearing the browser cache. If that does not work, I would recommend restarting your PC. Upon doing so, I was able to successfully publish my webmap as a Story map tour application.
Nick
Hi Scott,
Sorry I missed your post.
Map Tour implement responsive UI depending on browser resolution and can incorrectly detect a browser window that is tall but not very large as a mobile device. Your workaround is to reduce the window height, when the height will be smaller than the width, the builder will works.
Our most recent template Map Journal and Map Series don't have those issues. We will fix that in the next major version of Map Tour.