It might be an issue caused by a plugin or your theme.
We recommend installing this plugin: https://wordpress.org/plugins/health-check/
After you install and activate the above plugin it has a Troubleshooting mode which allows you to have a vanilla WordPress session, where all plugins are disabled, and a default theme is used, but only for your user – your visitors will still see the normal website. Please see more info here
An example of plugin which can cause the issue is called Slide Anything – Responsive Content / HTML Slider and Carousel and we recommend deactivating it.