Slides not updated

Hello,

I added a new slide and I saved it, but slider is not updated. I tried a few times. I cleared website cache.

I enclosed also error displayed in backend: https://ibb.co/gd2m0zk

Here is the error from log:
[22-Jun-2020 18:47:47 UTC] PHP Fatal error: Uncaught Error: Class ‘MetaSlider_Admin_Pages’ not found in /home/mazurki/domains/ogarniamsie.pl/public_html/wp-content/plugins/ml-slider/ml-slider.php:90
Stack trace:
#0 /home/mazurki/domains/ogarniamsie.pl/public_html/wp-includes/class-wp-hook.php(287): MetaSliderPlugin->setup(”)
#1 /home/mazurki/domains/ogarniamsie.pl/public_html/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters(NULL, Array)
#2 /home/mazurki/domains/ogarniamsie.pl/public_html/wp-includes/plugin.php(478): WP_Hook->do_action(Array)
#3 /home/mazurki/domains/ogarniamsie.pl/public_html/wp-settings.php(403): do_action(‘plugins_loaded’)
#4 /home/mazurki/domains/ogarniamsie.pl/public_html/wp-config.php(96): require_once(‘/home/mazurki/d…’)
#5 /home/mazurki/domains/ogarniamsie.pl/public_html/wp-load.php(37): require_once(‘/home/mazurki/d…’)
#6 /home/mazurki/domains/ogarniamsie.pl/public_html/wp-admin/admin-ajax.php(22): require_once(‘/home/mazurki/d…’)
#7 {main}
thrown in /home/mazurki/domains/ogarniamsie.pl/public_html/wp-content/plugins/ml-slider/ml-slider.php on line 90

Woocommerce: 4.1.1
Wp: 5.4.2
Metaslider: Last version