I am creating a figure with 6 filled contour plots and a color bar (so, 7 axes total). The function creating the figure loops over a list of variable pairs and arranges the axes in 3x2 pattern with colorbar at the bottom, with a call to figure.colorbar at the end taking the last contourf call's output as leading input.

The problem - all out-of-range colors appear to be colored in as the "adjacent" color in the colorbar, except for the very last contourf plot, which seems to work as expected. But, commenting out the line that creates the colorbar results in the last plot also being broken (no "extended" colors).

All of the calls to contourf (inside of the loop) look like this; the levels and corresponding colors are fixed
plot = axes.contourf(aggregates_xs, aggregates_ys, aggregates_zs, color_levels, colors = color_values, extend = 'both'
plot.cmap.set_over('red')
plot.cmap.set_under('blue')

matplotlib version 3.0.2 (same behavior in 2.0.2, but I didn't guess to try removing the colorbar before updating)