Shifted plots in combined axis plot in seaborn

I am trying to combine barplot and line plot in seaborn. However, the result which is shown below is that the line plot in shifted to the right and starts from '4' for no obvious reason (at least for me). The code I use is as follows:

fig, ax1 = plt.subplots(figsize = (10,8))
ax1 = sns.barplot(x = df['Month'],
                  y = df['M1'],
                  hue = df['Fabryka_MA'], 
                  ci=None)
ax1.legend_.remove()

ax2 = ax1.twinx()
ax2 = sns.lineplot(x = df['Month'], 
               y = df['M2'], 
               hue = df['Factory'], 
               ci = None, 
               legend = None)

ax2.grid(None)
plt.show()