To draw a Scatter- or Bubble-Diagram, data for the X- and the Y-Axis is neccessary to be set in correlation. If one or both of these measures is missing, an alternative mode will be used to draw the Bubbles. The so called Trellis Small Multiples Mode.
In this mode all data points will be drawn sorted by the Circle-Measure from high to low in small tiles. If there are too many data points to be drawn, the smaller ones will be summarized in the Rest tile.
Some options and features that are usable in the normal mode are deactivated while the Bubbles are in Trellis Small Multiples Mode.