Featured Slider not displayed

Sometimes, randomly, Featured Slider is not displayed on my website.
“Permalink to … ” is displayed instead
Please could you tell me how to correct this bug ? Thanx

Here below a screenshot

https://unecigaledanslafourmiliere.com/charly/slider.png

The page I need help with: [log in to see the link]