Hello,
I'm currently running python-control 0.8.3 on python 3.8.5.
When plotting 'root_locus' in a interactive python notebook, I get a plot way offset to the right, according to the image below:

The unexpected for me, though, is that when the exact same code was executed directly from the terminal, the plot was perfect.
The plot issues appears on every interactive notebook environment: jupyter notebook, jupyter lab and visual studio code's jupyter implementation. I'm running these versions of jupyter:
notebook 6.1.4
jupyter_client 6.1.7
jupyter_contrib_core 0.3.3
jupyter_core 4.6.3
jupyter_latex_envs 1.4.6
jupyterlab 2.2.8
jupyterlab_pygments 0.1.2
jupyterlab_server 1.2.0

here is the code for reproducing:

from control import *
import matplotlib.pyplot as plt

num = [25]
den = [1,6,25]
x1 = tf(num, den)
rlist, klist = root_locus(x1)
plt.show()