How to find an existing HTML element with python-selenium in a jupyterhub page?

I have the following construct in a HTML page and I want to select the li element (with python-selenium):

<li class="p-Menu-item p-mod-disabled" data-type="command" data-command="notebook:run-all-below">
    <div class="p-Menu-itemIcon"></div>
    <div class="p-Menu-itemLabel" style="">Run Selected Cell and All Below</div>
    <div class="p-Menu-itemShortcut" style=""></div>
    <div class="p-Menu-itemSubmenuIcon"></div>
</li>

I am using the following xpath:

//li[@data-command='notebook:run-all-below']

But the element does not seem to be found.

Complete, minimal working example code:

import time
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

driver = webdriver.Firefox()
driver.get("https://mybinder.org/v2/gh/jupyterlab/jupyterlab-demo/master?urlpath=lab/tree/demo")

# Wait for the page to be loaded
xpath = "//button[@title='Save the notebook contents and create checkpoint']"
element = WebDriverWait(driver, 600).until(
    EC.presence_of_element_located((By.XPATH, xpath))
)
time.sleep(10)
print("Page loaded")

# Find and click on menu "Run"
xpath_run = "//div[text()='Run']"
element = WebDriverWait(driver, 60).until(
    EC.element_to_be_clickable((By.XPATH, xpath_run))
)
element.click()
print("Clicked on 'Run'")

# Find and click on menu entry "Run Selected Cell and All Below"
xpath_runall = "//li[@data-command='notebook:run-all-below']"
element = WebDriverWait(driver, 600).until(
    EC.element_to_be_clickable((By.XPATH, xpath_runall))
)
print("Found element 'Run Selected Cell and All Below'")
element.click()
print("Clicked on 'Run Selected Cell and All Below'")

driver.close()

Environment:

• MacOS Mojave (10.14.6)
• python 3.8.6
• selenium 3.8.0
• geckodriver 0.26.0

Addendum

I have been trying to record the steps with the Firefox "Selenium IDE" add-on which gives the following steps for python:

sdriver.get("https://hub.gke2.mybinder.org/user/jupyterlab-jupyterlab-demo-y0bp97e4/lab/tree/demo")
driver.set_window_size(1650, 916)
driver.execute_script("window.scrollTo(0,0)")
driver.find_element(By.CSS_SELECTOR, ".lm-mod-active > .lm-MenuBar-itemLabel").click()

which, of course, also does not work. With that code lines I get an error

selenium.common.exceptions.NoSuchElementException: Message: Unable to locate element: .lm-mod-active > .lm-MenuBar-itemLabel

from How to find an existing HTML element with python-selenium in a jupyterhub page?