Series Data Column does not set the Series Data column

When trying to create a Chart, a Line chart for example, I can only set items I have set as a subtotal as a series; this is expected.

An unexpected behavior is that when I set "series data column" it sets the "label axis column" on the actual chart and that the "label axis column" control for creating sets the "series data column" on the actual chart. What I am saying is this: "series data column" should set the series of data that displays on the legend for a chart, and "label axis column" should set the labels on the "x-axis" of the chart.

Example: I am trying to create a chart that shows the number of users in a particular role over time. I want to have a "data axis" of total, a "label axis" of month names, and a "series data column" of role. This issue with "series data column" prevents me from creating this chart. The only chart I can create is one where I make the month the series and the role the label axis, which results in having a separate instance of the Month Name for every single day in the month that has a data point.

Not having this ability is preventing me from making this. Am I misunderstanding something?