If you are in build mode to update your survey while it is deployed and someone tries to access it to fill it out what happens: to the person filling it out and to the person in build mode?
When a respondent starts your survey, they are locked into a survey session and will see their survey as it existed when they started. They can submit their response without issue – similarly, you won’t see anything different if editing a deployed survey on the Build Page.
In general I know SurveyGizmo does not recommend editing live surveys but they have some best practices for this here:
My preference is to close the survey temporarily if I have to make any updates to it after it’s been launched to its intended audience.
Hope that helps!