So you’ve added your scrollbars to your widget layout somewhere? As I said before, SMultiLineEditableText will not do this for you, and neither will SMultiLineEditableTextBox if you provide custom scrollbars (as it’s assumed you want to place them at a custom location).
SMultiLineEditableText can appear to scroll even without having actual scrollbars.
The scrollbar padding is only used when SMultiLineEditableTextBox generates its own scrollbars, as it has no control over where your custom ones will be added.