You are using CDN, cache plugin and maybe server cache. I would recommend you to disable caching while you are making changes on the site, enable it once customization will be finished. We do not have any problems with the header builder on our test site, so likely it is cache/CDN effect on your side.
I’ve disabled Blur in slider settings – http://prntscr.com/rszbaz Please clear cache and check now.
As I can see, all required plugins are activated. Here you can find a list of such plugins https://www.8theme.com/documentation/xstore/plugins/included-plugins/ Recommended plugins can be installed / activated via Appearance > Install plugins, for example, Wishlist plugin. Do not activate new plugins unnecessarily, because every plugin slows down the site a bit.
Keep in mind that you need to build content using only one builder, don’t try to edit page that was created by WPBakery using Elementor. Our demo version uses WPBakery, so you can disable the Elementor plugin at all, or use it for new pages only.
Regards