Suddenly scroll bar vanished in the Survey Gizmo build page and final landing page. Please help.
What you’re describing sounds like an HTML issue. It sounds like you might have some broken HTML code in your survey build somewhere that’s causing conflicts with the way the survey displays.
I would recommend making a copy of your survey (so that you don’t mess up the original), then in the copy, go into Tools > Find & Replace, then click on “Show all text with HTML tags”. Remove the HTML from the survey bit by bit. After you remove each bit of HTML, view the survey in Build to see if the problem is fixed. Keep deleting HTML bit by bit until you the scroll bar is available again in Build, and you’ll know you found the culprit bad HTML. Once you find it, you can go back into your original survey and fix it in there.