On XEUS 0.23.9 I find that using the @interact decorator and sliders that they will appear fine and as expected, however when they are attached to figures they don't display properly.

Here is a minimal example that doesn't work on my system:

from __future__ import print_function
from ipywidgets import interact, interactive, fixed, interact_manual
import ipywidgets as widgets
import matplotlib.pyplot as plt
@interact(n=(1,7))
def plotN(n):
    vals = [i for i in range(n)]
    plt.plot(vals)

expected behaviour: img

actual behaviour: img