It seems that this is a caching problem. To solve this problem please go to Dashboard > Premium Addons for Elementor > Elements then click on ‘Save Settings’ after that go to your page – editing mode – then click on ‘Update’ then refresh the page. Everything will work well after you do these steps.
Concerning the inline documentation of ‘Slider Content’ section, we are currently doing some enhancements to all the inline documentation of our widgets, and this one will be replaced with the following sentence ‘Slider content is a templates. Save your own template and find it in Elementor library. Each template will be a slider content’.
This is a good chance to take your opinion about this one, what do you think about it?