I had a bar chart with two dimensions - and the labels were displayed correctly. The first dimension was the bar across the bottom (no label needed) and the last dimension differentiated different bars designated by colors in the legend. In this case, I had Chart Properties -> Dimensions -> For the second Used Dimension I had the Label box checked and the desired label listed. The legend label was displayed correctly on right side of chart.
Since then, I added several conditional dimensions to replace the first dimension, so there are several conditions that change what is showed along the X-axis, but the last dimension has stayed the same (Label box still checked). The problem is that the label at the top of the legend is no longer visible.