seaborn heatmap not displaying correctly

Question

for some reason, my heatmap is not displaying correctly anymore! It was working just fine even with 6 classes. Since the last time I used it, I've installed many packages ( including plotly), I don't know what exactly has caused this. How can I make the annotations and the x/y labels centered again. In both images, the exact same code is used.

    import matplotlib.pyplot as plt
    import seaborn
    conf_mat = confusion_matrix(valid_y, y_hat)
    fig, ax = plt.subplots(figsize=(8,6))
    seaborn.heatmap(conf_mat, annot=True, fmt='d',xticklabels=classes, yticklabels=classes)
    plt.ylabel('Actual')
    plt.xlabel('Predicted')
    plt.show()