I am trying to create a trend line chart, but not sure why the chart is being split into 2 rows as below. I only have one dimension and one measure. I am trying to show a small chart (sales trend by month).
These are not 2 rows. In fact, it only displays an expression by 1 dimension. As the widht of your visualization is too small with respect to the whole x-axis range, it creates an horizontal scrolling bar beneath your trend line.
Try expanding the visualization and scroll the horizontal bar to see the whole range of values.