To solve this problem you need to add heigh 100% to the 3 elements in the slick carousel.

Add this code below after the end of your css code and will appear again:

/* Solutions */
.slick-list,
.slick-track,
.slick-slide h3 {
   height: 100%;   
}

Reference link: https://github.com/kenwheeler/slick/issues/367