I solved this by deselecting ‘Use Autolayout’ in the File Inspector pane of main view within the Scroll View.
If you want to keep ‘Autolayout’ enabled, try ‘Editor -> Reslove Autolayout Issues -> Add Missing Constraints’. The key constraint appears to be ‘Bottom Space to: Superview and in my case was -300, giving 300 scroll space on the botton of the view.