Navigate to WPBakery Page Builder Settings > General Settings and disable the "Legacy X Integration".
Regarding the missing content in visual composer, please increase your PHP memory limit, if it did not work, please do testing for a plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it's fixed, you'll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
Let us know how it goes,