Yes, I did obtain the same result as you, when the color of each of the three last bubbles are "manually" changed, and even if the color chosen is the default color of the series [see lines 9-11].
One detail: when two bubbles are centered *without having changed their default color*, the color do not sum, but also the label of the second bubble does not appear [see lines 1-2] and the bubble cannot be selected in the chart (for example by using the TAB button from another bubble selected). All is like the line of the second bubble in the data table would not be red when building the chart (the second bubble does not seem to exist in the chart). In fact, the transparency of the color does not change this behaviour [see the second chart, which has been obtained by copying the first one and removing transparency of the color of the series].