The scenario of the issue is something similar to the following: You have the slider created on your backend, but when place and check on the frontend the animations of the first slide doesn't start, it only seems that it stucked. The 99% of that is caused that the Start Slideshow or the Animate starting slide parameters of the Slider settings/Slideshow tab are disabled. So you need to enable those parameters and then the slider will start animated.

Slideshow settings
Slideshow settings