A Flex Repeater with flexWrap set to ‘wrap’ will show a scrollbar for the non-direction axis (horizontal scrollbar for ‘column’ direction on the repeater) if the viewport is less than size of the view being displayed. However, the scrollbar does not appear in the same situation if flexWrap is set to nowrap.
Additionally, the wrap location / scrollbar appearance is based on the default size, not the actual size of the content. For example, if the repeated view width is currently 500, but the default size is 400, when the flex repeater wraps, it will start the next column at 400, cutting off the last 20% of the first column of views.
In my case, I have a vertical flex repeater that contains a set of horizontal flex repeaters (each the same size).