Thanks for contacting us again.
Did you follow these steps (https://theme4press.com/docs/setting-up-the-sliders/bootstrap-slider/) to set up the sliders? Kindly could you check if there’s any third party plugin conflicting with the theme. Try to deactivate them and check again, if the issue is resolved, reactivate them one by one to identify the culprit.
Let me know how it goes.