I was actually able to resolve my issue by not using the visual.ElementArrayStim class, but used a for loop to change the height and width of the bars.
image.draw()
barSizes = [...]
for i in barSizes:
bar.width = barSizes[0]
bar.height = barSizes[1]
bar.draw()
win.flip()
The idea came from the last comment of this thread.