In the XYBar renderer its is checked if the label fits the inside of a bar to decide if it needs to be truncated or even not shown at all, see XYBarRenderer#calculateLabeltoDraw(...).
This method used the RectangularShape#contains(Rectangle2D) method, but this method takes the x,y offset into account which is not valid as only the dimensions of the rectangle should be considered.

This leads to strange effects like labels be positioned on their fallback locations or not shown at all.