Under the tasks column, you are able to preview a survey by clicking on "view." If it results in the screen below, it may be due to a request for authentication.
Open Survey Flow in edit mode.
Determine if any requests would interrupt a preview, such as a "Branch on Successful Authentication"
For one specific survey, it was an SSO Authentication request to capture the respondent's University InternetID as part of their responses. It was based on steps found here: http://its.uiowa.edu/support/article/100526
Consider removing the Authentication step for the duration of editing and add it back in when needed before distributing.