pp.finalize() adding one more data point

[tomalf2]

Hello,
I've noticed that while the plot is being updated (i.e. calling pp.update()) the plot appears correct. But when calling pp.finalize(), a line connecting the first and last datapoint appears (see the straight blue and orange lines). The issue is documented in the attached pictures.

My code is pretty straightforward.

pp = ProgressPlot(plot_names=["Reconstruction loss", "Total loss"], 
                            line_names=['Training', 'Validation'])
for epoch in range(1, self.num_epochs + 1):
    train_rec, val_rec, train_loss, val_loss = ....
    pp.update([
                        [train_rec, val_rec],
                        [train_loss, val_loss]
                    ])
pp.finalize()

What might be the issue?