I had exactly the same problem, and these lines fixed the problem:
from matplotlib.ticker import ScalarFormatter
y_formatter = ScalarFormatter(useOffset=False)
ax.yaxis.set_major_formatter(y_formatter)
I had exactly the same problem, and these lines fixed the problem:
from matplotlib.ticker import ScalarFormatter
y_formatter = ScalarFormatter(useOffset=False)
ax.yaxis.set_major_formatter(y_formatter)