CSS file not saving properly

After updating the settings for my slider, the CSS isn’t showing the new settings; it’s all just blank.

This is what the Generated CSS shows:

.smooth_slider{}
.smooth_slider .sldr_title{}
.smooth_slider .smooth_slideri{}
.smooth_slider .smooth_slider_thumbnail{}
.smooth_slider .smooth_slideri h2{}
.smooth_slider .smooth_slideri h2 a{}
.smooth_slider .smooth_slideri span{}
.smooth_slider .smooth_slideri p.more{}
.smooth_slider .smooth_next{}
.smooth_slider .smooth_prev{} .smooth_slider .smooth_slider_eshortcode{} .smooth_slider .smooth_more a{}

How can I fix this? I’m using Smooth Slider version 2.8.4.

https://wordpress.org/plugins/smooth-slider/