Cannot preview post drafts or view published posts – infinite load

Disabled all plugins – issue persists
Switch theme – posts load
Enable all plugins in different theme – posts load
Reenable Highend theme, with or without plugins (including Highend required plugins) – posts do not load

In addition, WPBakery Page Builder Version 6.8.0 indicates a new version is available but cannot be updated from plugins, from Highend plugins nor manually since it came with the bundle and must be purchased again from source:

There is a new version of WPBakery Page Builder available. View version 6.9.0 details. Automatic update is unavailable for this plugin. Update through Highend Plugins.

v6.8.0 is only option in Highend Plugins (deactivating and reactivating changes nothing.

For support from the vendor, it will cost an additional $56 over the price of this theme.