Hello All -
I've got a dynamic scale bar in a map book of data-driven pages. The scale bar is positioned right-justified over the data frame with its bottom-right Anchor Point selected in Properties > Size and Position tab > Position field. After I step through a few data-driven pages the scale bar will begin to drift to the right, further with every page. In the example below, the right side of the scale bar was originally vertically aligned with the scale-text box above it.
As I backtrack through those same pages it continues its rightward drift. The scale bar will eventually walk off the page. This doesn't happen when it is left-justified.